Nbde Released-Anatomy

Front 1

A disturbance in cartilage formation in a fetus results in deformities of the
1. sphenoid and zygomatic bones.
2. axial skeleton and the base of the skull.
3. axial skeleton and the flat bones of the skull.
4. petrous portion of the temporal bones and the parietal bones.

Back 1

The correct answer is choice 2= AXIAL SKELETON AND THE BASE OF THE SKULL
. Some bones in the human skeleton are formed by ossification of a cartilaginous model while others are not. When the bone is formed in a connective tissue other than cartilage, it is termed intramembranous ossification rather than cartilage ossification. Disturbance in cartilage formation will affect those bones produced on a cartilage model, but not those produced intramembranously. Let's check the choices. In general, the axial skeleton and skull base are ossified from cartilage models, so choice 2 is correct. Choice 3 is incorrect as most flat bones of the skull are intramembranous, not cartilaginous. Choice 4 is incorrect. The petrous portion of the temporal bone is from a cartilage model, while the squamous part is membranous. The parietal hones ossify intramembranously. Choice 1 is also incorrect. The sphenoid is mostly cartilaginous in ossification, but part of the greater wing is membranous. However, the zygomatic bone is intramembranous. So again the correct answer to question is choice 2.

Front 2

Tendons are comprised of which of the following types of collagenous connective tissue?
A. Areolar
B. Reticular
C. Dense regular
D. Dense irregular

Back 2

The correct answer is choice C, Dense regular.
Tendons, as well as ligaments, fasciae and aponeuroses, are constructed of dense regular connective tissue. In this tissue, collagen fibers are arranged in a highly regular way. In tendons, the collagen fibers are parallel and resist pulling forces. Fibroblasts lie in rows between the collagen fiber rows. Dense irregular fibrous tissue is found in the dermis of skin and the capsules of many organs. The collagen fibers are thicker and are arranged in a more random pattern. Reticular connective tissue is composed of thin fibers and forms the framework for lymphoid organs and the stroma of the liver. Areolar connective tissue is another term for loose connective tissue, in which fibers are fewer, and matrix greater. So the correct answer to question is choice C

Front 3

The alveolar bone proper (cribriform plate) usually consists of
1. woven bone.
2. bundle bone only.
3. lamellar bone only.
4. bundle bone and lamellar bone.

Back 3

The correct answer is choice 4, bundle bone and lamellar bone... Let's review the choices. Woven bone is bone with a delicate framework of trabeculae, or cancellous bone. It contains many vascular spaces and is found in fetal bones when cartilage ossifies and in early repair of fractures. Choice 2, bundle bone, is a term which refers to bone adjacent to the periodontal ligament and contains Sharpey's fibers. It is not unique to the mandible, but is also found where muscles and ligaments attach to bone. Choice 3, lamellar bone, refers to concentric rings of bone laid down around central canals of haversian systems. This is known as compact bone. The correct choice is choice 4. The socket around the tooth, which is found in the alveolus of the mandible, contains both lamellar or compact bone and bundle bone with Sharpey's fibers of the periodontal ligament.

Front 4

The anterior interventricular (descending) artery is accompanied by the
1. small cardiac vein.
2. middle cardiac vein.
3. great cardiac vein.
4. coronary sinus.

Back 4

The correct answer is choice 3, the great cardiac vein... The anterior interventricular descending artery, a branch of the left coronary artery supplies blood to both the right and left ventricles. It follows the interventricular septum or sulcus to anastomose with the posterior interventricular branch of the right coronary artery. It is accompanied on this course by the great cardiac vein, choice 3. The small cardiac vein, choice 1, accompanies the marginal branch of the right coronary artery. The middle cardiac vein, choice 2, courses the heart with the posterior interventricular or descending artery. The coronary sinus, choice 4, receives most of the venous return from the epicardium and myocardium. Its tributaries include the great cardiac vein, the middle cardiac vein and the oblique vein. So the correct answer to question is choice 3.

Front 5

The apical cytoplasm of active serous glandular cells is typically filled with which of the following?
A. Large amount of DNA
B. Abundance of ribosomes
C. Abundance of mitochondria
D. Abundance of lipid droplets
E. Abundance of zymogen granules

Back 5

The correct answer is choice E, zymogen granules... Let's use process of elimination here. Cytoplasm, in general, will not contain DNA, which is confined to the nucleus (and a small amount within mitochondria). Ribosomes produce protein, so large numbers of ribosomes should be found in cells secreting a lot of protein. Serous saliva is mostly water, salts, bicarbonate,and a small amount of amylase, so there is not much protein here. While the serous gland cells produce serous saliva, most of the work of adjusting its ionic content is acomplished by striated duct cells, which have a large number of energy-furnishing mitochondria. Large numbers of mitochondria are not found in the serous cells themselves. Lipid droplets will not be found because neither mucous nor serous saliva contains much lipid. Serous secretions are formed and secreted by way of zymogen granules, which are abundant at the cell base and then migrate to the secretory surface where their secretions are released. The correct answer to question is choice E.

Front 6

The area at which calcification of a tooth begins is the
1. root.
2. enamel matrix.
3. cementoenamel junction.
4. dentinoenamel junction

Back 6

The correct answer is choice 4, the dentoenamel junction... The calcification of a tooth begins at the dentinoenamel junction, choice 3. Maturation of the enamel is characterized by the gradual completion of mineralization. At each level, maturation begins at the dentinal end of individual enamel rods. The actual sequence of maturing rods, however, is from cusps down towards the cervical line. So. the correct answer to question is choice 4.

Front 7

A fracture of the hamulus affects the action of which of the following muscles?
A. Superior constrictor of the pharynx
B. Levator veli palatini
C. Tensor veli palatini
D. Salpingopharyngeus
E. Buccinator

Back 7

TENSOR VELI PALATINI

The correct answer is choice C. The tendon of tensor veli palatini hooks around the pterygoid hamulus to insert into the palatal aponeurosis. Choice A is incorrect. The superior constrictor inserts into the pharyngeal tubercle of the occipital bone and the midline pharyngeal raphe. Choice B is incorrect. The levator veli palatini (levator palati) arises from the cartilaginous rim of the auditory tube and inserts directly into the palatal aponeurosis. It does not have contact with the hamulus. Choice D is incorrect. Salpingopharyngeus passes from the toms tubarius to the wall of the pharynx. Choice E is incorrect. Buccinator originates from the pterygomandibular raphe and inserts by blending with other muscles of facial expression around the corner of the mouth in an arrangement known as the modiolus.

Front 8

A major sensory innervation of the temporomandibular joint is derived from the
1. great auricular nerve.
2. auriculotemporal nerve.
3. inferior alveolar nerve.
4. temporal branches of the facial nerve.

Back 8

AURICULOTEMPORAL NERVE

The correct answer is choice 2. The temporomandibular joint is innervated by nerves from the auriculotemporal and masseteric branches of the mandibular nerve or V3. Choice 1, the greater auricular nerve, exits the spinal cord from levels C2 and C3 and innervates cutaneous areas of the neck, lower face and posterior head. Choice 3, the inferior alveolar, is a branch of the mandibular nerve or V3 which innervates the mandibular teeth, alveolar bone and gingiva. Choice 4, the temporal branches of the facial nerve, innervate the facial muscles above the palpebral fissure of the eye. So the correct answer to question 46 is choice 2.

Front 9

A patient who has damage to the right hypoglossal nerve will protrude the tongue
A. upward.
B. downward.
C. straight forward.
D. toward the right side.
E. toward the left side.

Back 9

TOWARS THE RIGHT

The correct answer is choice D. If the muscles of the right side of the tongue are damaged, the effect of unopposed action of the muscles on the unaffected side will be to protrude the tongue across the midline. Hence the patient sticks out his tongue toward the side of the lesion. Choice A is incorrect. Contraction of genioglossus, the largest and most powerful of the tongue muscles, draws the root of the tongue forward and causes the tip to protrude. Choice B is incorrect. See (A) above. Choice C is incorrect. For the tongue to protrude straight forward, the genioglossi of both sides must be functional. Choice E is incorrect. In a case of unilateral damage to the hypoglossal nerve, the tongue protrudes to the same side as the lesion.

Front 10

A patient with absent direct and consensual light reflexes, but normal eyesight, is most likely to have a lesion on what cranial nerve?
A. Abducens nerve
B. Oculomotor nerve
C. Optic nerve
D. Trochlear nerve
E. Trigeminal nerve

Back 10

OCULOMOTOR NERVE

The correct answer is B. The oculomotor nerve (choice B) functions to lift the upper eyelid, turn the eyeball upward, downward and medially, constricts the pupil and accommodates the eye. When this nerve is damaged both the direct and consensual light reflexes may be absent. In the direct reflex, the pupil will contract when a light is shone in the patient's eye. The consensual light reflex is seen when a light is shone in one eye and the observer notes the contraction of the pupil in the other eye. The abducent nerve (choice A) functions to turn the eyeball laterally. The optic nerve (choice C) is involved with vision and carries visual messages in nervous form to the brain for interpretation. The trochlear nerve (choice D) functions to turn the eyeball downward and laterally. The trigeminal nerve (choice E) is involved in the corneal reflex.

Front 11

A portion of which of the following muscles has fibers inserting into the articular disk of the temporomandibular joint?
1. Upper head of the lateral pterygoid
2. Lower head of the lateral pterygoid
3. Deep head of the medial pterygoid
4. Superficial head of the medial pterygoid

Back 11

UPPER HEAD OF THE LATERAL PTERYGOID

The correct answer is choice 1. The only muscle which connects to the articular disk of the temporomandibular joint is the lateral or external pterygoid. The upper head of this muscle inserts through the fibrous capsule of the joint and into the articular disk. Choices 3 and 4 are incorrect. The medial or internal pterygoid is a jaw elevator or closing muscle. Both the superficial and deep head of the medial pterygoid insert on the medial surface of the mandible. The medial pterygoid closes (elevates) the mandible, and the lateral pterygoid acts in opening (depressing) and protruding. The primary retruding muscle is the temporalis (posterior fibers). Anyway, the correct answer to question is choice 1.

Front 12

A tumor of the maxillary sinus may cause an overflow of tears by exerting pressure on the
1. lacrimal gland.
2. lacrimal puncta.
3. conjunctival sac.
4. nasolacrimal duct.

Back 12

NASOLACRIMAL DUCT

The correct answer is choice 4. The maxillary sinus is the largest of the paranasal sinuses. It is pyramidal in shape and lies within the maxillary bone. Anteriorly, it extends to the nasolacrimal duct as a lacrimal recess. The tumor of the maxillary sinus may cause an overflow of tears when the tumor exerts pressure in the lacrimal duct, choice 4. The lacrimal duct functions as a drain into the nasal cavity and when a blockage occurs, tears cannot drain into the nose and therefore will run out onto the cheek. Lacrimal glands, choice 1 located in the superior and lateral region of the orbit, produce tears. The lacrimal puncta, choice 2, is an opening marking the beginning of the lacrimal canaliculus through which lacrimal fluid is transported to the lacrimal sac. Conjunctival sac, choice 3, is a space enclosed by the eyelid and it opens into the skin of the face at the palpebral fissure. So the correct answer to question is choice 4.

Front 13

cidophils (alpha cells) of the hypophysis secrete
1. insulin.
2. thyroxin.
3. sex hormone.
4. growth hormone.

Back 13

GROWTH HORMONE
cidophils (alpha cells) of the hypophysis secrete
1. insulin.
2. thyroxin.
3. sex hormone.
4. growth hormone.

Front 14

All of the following structures are concerned with development of the tongue EXCEPT the
1. copula.
2. macula.
3. tuberculum impar.
4. second branchial arch.
5. third branchial arch.

Back 14

MACULA

The correct answer is choice 2. Let's review the contribution of each choice. The first branchial arch produces an elevation known as the tuberculum impar, choice 3, which will form the anterior two-thirds of the tongue served by the mandibular nerve. The second arch, choice 4, contributes only the branch of its nerve, the chorda tympani of the facial nerve for taste sensation to the anterior two-thirds. The third branchial arch (choice 5) contributes to the hypobranchial eminence which, together with the copula (choice 1), give rise to the posterior one-thhd of the tongue. The macula, choice 2, is not involved in tongue formation. The macula can be found in the inner ear, in the retina and in the kidney, but it is not involved in tongue formation. So the correct answer to question is choice 2.

Front 15

All of the following structures can be seen in a histologic examination of the adult parotid gland EXCEPT
1. striated ducts.
2. serous demilunes.
3. intercalated ducts.
4. myoepithelial cells.
5. granular serous cells.

Back 15

SEROUS DEMILUNES

The correct answer is choice 2. The parotid gland produces serous secretions. Granular serous cells, choice 5. produce the original secretion which travels through intercalated ducts (choice 3) to the striated ducts (choice 4). In the striated ducts ion exchange occurs and the final ionic concentrations of saliva arc cstahlishcd. Choice 4, myoepithelial cells are involved in contraction and movement of the saliva out of the acini, where the saliva is first produced. Choice 2. serous demilunes, are found in the submaxillary gland, a mixed mucous and serous gland. They produce serous secretions and surround mucous acini. Serous demilunes are absent in the parotid gland. The parotid is almost entirely serous. so dcmiluncs (which surround mucous acini) are not found there. So the correct answer to question is choice 2.

Front 16

An example of fibrous connective tissue of the reticular type would be
A. Adipose
B. Bone marrow
C. Capsules of organs
D. Dermis of the skin
E. Tendons

Back 16

BONE MARROW

The correct answer is B. Fibrous tissues are categorized according to their content of fibers. The two basic types of fibrous tissue are loose fibrous tissue and dense fibrous tissue. Loose fibrous tissue includes reticular tissues, such as bone marrow (choice B), lymph nodes and the spleen. Other forms of loose connective tissue include adipose tissue (choice A) and areolar tissue which is found in the capsules of organs (choice C). Dense fibrous tissue is subdivided into two types of tissue: unorganized dense fibrous tissue, such as the dermis of the skin, (choice D) and organized dense fibrous tissue, such as the tissue found in tendons (choice E).

Front 17

An individual who loses the ability to swallow food most likely has a lesion on
A. Cranial nerve VI
B. Cranial nerve VII
C. Cranial nerve VIII
D. Cranial nerve IX
E. Cranial nerve X

Back 17

CN IX

The correct answer is D. The glossopharyngeal nerve or cranial nerve IX (choice D) innervates the pharynx and posterior portion of the tongue. Therefore, if an individual loses their ability to swallow food, they most likely have a lesion on cranial nerve IX. Cranial nerve VI (choice A) is primarily responsible for eyeball movements and proprioception. Cranial nerve VII (choice B) innervates various facial muscles and the taste from the anterior portion of the tongue. Cranial nerve VIII (choice C) is involved with one's sense of hearing and equilibrium and cranial nerve X (choice E) or the Vagus nerve innervates various organs in the viscera.

Front 18

An organ with a retroperitoneal location that can be approached surgically without violating the continuity of the peritoneum is the
1. ovary.
2. kidney.
3. spleen.
4. gallbladder.

Back 18

KIDNEY

The correct answer is choice 2. Retroperitoneal structures such as the kidney are located dorsal to the dorsal peritoneum of the abdominal cavity. They lie on the ventral surface of the quadratus lumborum muscle just lateral to the psoas muscle and vertebral column. As such, they can be approached surgically from the dorsal side or back. Choice 1, the ovary, is not usually retroperitoneal and peritoneum would have to be cut in order to reach it. A retroperitoneal ovary is an abnormality. Similarly, neither the spleen nor gall bladder are retroperitoneal and are suspended by mesentery from the peritoneum. So the correct answer to question is choice 2.

Front 19

Apical abscesses on certain teeth have a marked tendency to produce cervical spread of infection that occurs most rapidly in abscesses of
1. mandibular incisors.
2. mandibular canines.
3. maxillary premolars.
4. mandibular second and third molars

Back 19

MANDIBULAR SECOND AND THIRD MOLARS

The correct answer is choice 4. This is something that you will tend to see clinically soon. Anyway certain apical abscesses have greater potential for spreading to the cervical or neck area than others. In particular, mandibular second and third molar infections may travel down fascial planes into the neck. Since three of these fascial planes form the visceral compartment which opens into the thorax, dental infections can on occasion even enter the superior mediastinum of the thorax. The superior mediastinum contains many crucial structures, including the aortic arch, the superior vena cava. the vagus and phrenic nerves, and many other structures. Of the other answer choices, note that maxillary teeth are not likely to lead to cervical fascial planes and that mandibular incisors and canines. being in the same general anatomic area, are not therefore likely to be the correct answers. Anyway, the correct answer to question is choice 4.

Front 20

As a result of a mandibular block injection, a patient has developed a paralysis of the muscles of facial expression. Where was the anesthetic solution most likely deposited?
1. lnto the parotid gland
2. Near the chorda tympani
3. lnto the pterygoid plexus
4. Through the mandibular notch

Back 20

INTO THE PAROTID GLAND

The correct answer is choice 1. All of the muscles of facial expression are innervated by the facial nerve. cranial nerve VII. It exits the skull via the stylomastoid foramen and passes anterolaterally through the parotid gland. It crosses superficial to the external carotid artery and the retromandibular vein. It breaks into a number of branches which emerge separately from the gland to supply the muscles of facial expression on their deep surfaces. Therefore, if paralysis were to develop as a result of a mandibular block injection, the anesthetic solution is probably deposited in the parotid gland, choice 1. The chorda tympani, choice 2, a branch of the facial nerve, cranial nerve VII, conveys taste sensation from the anterior two thirds of the tongue. The pterygoid plexus, choice 3, a network of veins, lies in close association with the lateral pterygoid muscle and the middle portion of the maxillary artery. It receives drainage from the veins of the nasal cavity, oral cavity and paranasal sinuses. Injection through the mandibular notch, choice 4, will not result in facial paralysis since it will already be past the major branches of the facial nerve. So the correct answer to question is choice 1.

Front 21

As a tooth undergoes attrition with age and with use, it maintains contact with its antagonist. Which of the following describes how this phenomenon occurs?
1. The tooth forms additional apical dentin.
2. There is continual apposition of bone at the fundus of the tooth socket.
3. There is continual apposition of cementum in the tooth's apical region.
4. None of these

Back 21

CONTINUAL APPOSITION OF CEMENTUM IN THE TOOTH'S APICAL REGION.

The correct answer is choice 3. The wear of teeth by attrition with age is a physiologic and regular occurrence. Contact between teeth of opposing arches is kept by active eruption. This is achieved by compensatory deposition of cementum at the apical region of the root, choice 3. Choices 1 and 2 are incorrect because neither dentin nor bone is added in order to make the tooth erupt further. So the correct answer to question is choice 3.

Front 22

As demonstrated by the pattern of sensory innervation, which of the following branchial arches are concerned in development of the tongue?
A. First and second only
B. First, second, and third
C. Second and third only
D. Second, third, and fourth
E. Third and fourth only

Back 22

FIRST SECOND AND THIRD* I BELIEVE 4TH IS ALSO

The correct answer is choice B. General sensation from the anterior two-thirds of the tongue is conveyed by the lingual branch of V3. CN V is the nerve of the first arch. Taste from the anterior two-thirds of the tongue is conveyed by chorda tympani, a branch of CN VII. CN VII is the nerve of the second arch. Both general sensation and taste from the posterior one-third of the tongue are conveyed by CN IX. CN IX is the nerve of the third arch. Choice A is incorrect. The first and second arches are concerned in development of the anterior two-thirds of the tongue. Choice C is incorrect. Branches of the nerves from arches II and III convey taste from different parts of the tongue. Choice D is incorrect. Branches of the nerves of arches II, III and IV convey taste from all parts of the tongue, but general sensation from the anterior two-thirds is not conveyed by any of these nerves. Choice E is incorrect. Branches of the nerves from arches III and IV convey sensory information from the posterior aspect of the tongue.

Front 23

As the subclavian vein crosses the first rib, it lies
A. anterior to the anterior scalene muscle.
B. posterior to the anterior scalene muscle.
C. posterior to the posterior scalene muscle.
D. between the anterior and the posterior scalene muscles.
E. between the scalene posterior and the levator scapulae muscles.

Back 23

ANTERIOR TO THE ANTERIOR SCALENE MUSCLE
The correct answer is choice A.
The subclavian vein passes anterior to the anterior scalene muscle in the root of the neck. Upon reaching the outer border of the first rib, it becomes the axillary artery. Choice B is incorrect. The subclavian artery and the brachial plexus pass posterior to scalenus anterior. Choice C is incorrect. The subclavian artery and the trunks of the brachial plexus emerge into the posterior triangle by passing between the anterior and middle scalene muscles. Choice D is incorrect. Choice E is incorrect.

Front 24

At a muscle-tendon junction, the union is made by
1. myofibrils connecting with collagenous fibrils of the tendon.
2. an abundance of reticular fibers in the area of the junction.
3. a continuity of connective tissue sheaths of the muscle with those of the tendon.
4. a special thickening of sarcoplasm that unites with collagenous fibrils of the tendon.

Back 24

A CONTINUITY OF CONNECTIVE TISSUE SHEATHS OF THE MUSCLE WITH THOSE OF THE TENDON.

The correct answer is choice 3. When muscles attach to tendons, the connective tissue surrounding the muscle continues uninterrupted around the tendon. In the tendon, the collagen fibers unite at one end to the bone or other material that the tendon attaches to and at the other end to the sarcolemma of the muscle fiber. There is no direct connection of the muscle fiber to the collagen fiber. Therefore, choice 1 is incorrect. Choice 2 is also incorrect. Reticular fibers form the meshwork inside lymph nodes, which acts as a foundation for filtration of lymph, and reticular fibers are also found in the tunica media of arteries. Choice 4 is incorrect. Although the sarcolemma of the muscle attaches to the collagen fibers, the sarcoplasm or cytoplasm of the muscle fiber does not. So the correct answer to question is choice 3.

Front 25

Bacteria are frequently ingested by
1. mast cells.
2. fibrocytes.
3. small lymphocytes.
4. basophilic leukocytes.
5. neutrophilic leukocytes.

Back 25

NEUTROPHILS

The correct answer is choice 5. Neutrophils or PMNs or polymorphonucleocytes actively ingest bacteria through the process of phagocytosis. Neutrophils are granulocyte-type white blood cells. Other granulocytes are eosinophils and basophils. Choice 4, basophils, contain heparin and histamine, but do not phagocytize bacteria. Choice 1, mast cells, are involved in the immune response and also contain heparin and histamine. They are found in large numbers in connective tissue. Choice 2, fibrocytes, produce connective tissue fibers. Choice 3, lymphocytes, are involved in immune response and serve a variety of defensive functions. Blymphocytes may become plasma cells and produce antibodies. T-lymphocytes may assist B-lymphocytes or may destroy foreign cells. Anyway, the correct answer to question is choice 5.

Front 26

Basket (myoepithelial) cells are located in the
1. periodontal ligament.
2. lumen of secretory acini.
3. lamina propria of gingiva.
4. lumen of intercalated ducts.
5. spaces between the basal lamina and the secretory cell membrane.

Back 26

SPACES BETWEEN THE BASAL LAMINA AND THE SECRETORY CELL MEMBRANE

The correct answer is choice 5. Basket cells or myoepithelial cells can be found in the secretory portions of some exocrine glands. These cells function as the contractile elements of the gland and are located between the secretory cell membrane and the basal lamina, choice 5. So the correct answer to question is choice 5.

Front 27

The arterial supply of the submandibular gland is from which branch of the external carotid artery?
1. Ascending pharyngeal
2. Superior thyroid
3. Maxillar
4. Facial

Back 27

The correct answer is choice 4, the facial artery... The external carotid artery divides into multiple branches. Among the most important are the superior thyroid to the thyroid and surrounding tissue (choice 2); the lingual to the tongue; the facial to the pharynx, soft palate, tonsil. submandibular gland, upper lip and surrounding areas (correct choice 4); the ascending pharyngeal to the pharynx, palatine tonsil and auditory tube (choice 1); and the maxillary to the middle ear, skull. periosteum, mandible, teeth, chin, muscles of mastication, soft palate and maxillary sinus. among other areas (choice 3). So the correct answer to question is choice 4.

Front 28

The bony floor of the nasal cavity is formed by the
1. palatine process of the maxilla and the vertical part of the palatine.
2. palatine process of the temporal and the horizontal part of the palatine.
3. vomer and the vertical part of the palatine.
4. palatine process of the maxilla and the horizontal part of the palatine.

Back 28

The correct answer is choice 4, the palatine process of the maxilla and the horizontal part of the palatine. The bony floor of the nasal cavity is formed by two bones. The palatine bone is L-shaped with a horizontal and vertical plate. The horizontal plate has a smooth upper nasal surface and borders anteriorly on the palatine process of the maxilla. The two palatine processes of the maxilla fuse in the midline at the anterior nasal spine. So sections of the palatine and maxillary bones form the nasal floor. Choice 1 is incorrect because the horizontal, not vertical, process of the palatine is involved. Choice 2 is incorrect because the temporal bone is not involved in composing the floor of the nasal cavity. Choice 3 is incorrect. The vomer and vertical parts of the palatine bone are not involved in forming the floor of the nose. The vertical or perpendicular plate of the palatine forms part of the lateral wall of the nasal cavity, while the vomer forms part of the nasal septum. So the correct answer to question is choice 4.

Front 29

The branch of the ophthalmic artery that pierces the optic nerve is the
1. supraorbital.
2. anterior ciliary.
3. anterior ethmoidal.
4. central artery of the retina

Back 29

The correct answer is choice 4, the central artery of the retina... The ophthalmic artery, a branch of the internal carotid artery, has many tributaries. Its first branch, the central artery of the retina, choice 4, arises in the optic canal and runs with the sheath of the optic nerve. It pierces the nerve about half way along its intraorbitai course and runs in the center of the nerve to supply the retina. The supraorbital artery, choice 1, runs between the levator palpebrae superioris and the periosteum to the supraorbital foramen to supply the skin of the forehead and the anterior front of the scalp. The anterior ciliary artery, choice 2, pierces the sclera behind the corneal scleral junction to join the greater arterial circle of the iris. The anterior ethmoidal artery, choice 3, passes through the anterior ethmoidal foramen on its course to the tip of the nose to supply the frontal sinus, the nasal mucoperiosteum and the skin of the nose. So the correct answer to question is choice 4.

Front 30

The buccinator muscle is supplied by which of the following nerves?
A. Facial
B. Lingual
C. Spinal acessory
D. lnferior alveolar
E. Buccal nerve of the trigeminal

Back 30

The correct answer is choice A, the facial nerve... The buccinator is a muscle of facial expression, derived from the second pharyngeal arch. It is supplied by CN VII, the nerve of the second arch. Choice B is incorrect. The lingual nerve is a sensory branch of V3. Choice C is I incorrect. The spinal accessory supplies sternocleidomastoid and trapezius. Choice D is incorrect. The inferior alveolar nerve is a branch of V3 which conveys sensory information from the mandibular teeth and gingiva. It has a motor branch, the mylohyoid neve, which supplies mylohyoid and anterior belly of digastric. Choice E is incorrect. The buccal branch of V3, or "long buccal" nerve is a sensory nerve which supplies the skin of the cheek and the buccal mucosa

Front 31

The calcified bodies sometimes found in the PDL are BEST described as which of the following?
A. Cementicles
B. Denticles
C. Bone
D. Enamel pearls
E. Mineralized interstitial tissue

Back 31

The correct answer is choice A, cementicles... Cementicles are formed by cementoblasts, and are small isolated pieces of cementum found on x-ray, located in the PDL. Denticles are small isolated pieces of cementum, formed by odontoblasts and found on x-ray, located within the pulp. Isolated pieces of bone are not found unless broken off during surgical procedures. Enamel pearls are isolated pieces of enamel, formed by ameloblasts, located on or close to the tooth crown. The correct answer to question is choice A

Front 32

Calcium ions are sequestered by
A. T-tubules.
B. sarcoplasm.
C. sarcosomes.
D. myofibrils.
E. sarcoplasmic reticulum.

Back 32

SACROPLASMIC RETICULUM

The correct answer is choice E. Sarcoplasmic reticulum is specialized endoplasmic reticulum found in muscle cells, which serves as a reservoir for calcium ions. These ions are released to begin muscle contraction. Myofibrils are the smallest units of contraction visible under the light microscope. Multiple myofibrils make up the myofiber, or muscle cell. The myofibril is composed of myofilaments of two types, actin and myosin. The cell membrane is called the sarcolemma, and the cytoplasm is the sarcoplasm. Sarcosomes are mitochondria of the muscle cell. T-tubules are invaginations of the sarcolemma, and carry stimulation from nerve cells into the sarcoplasmic reticulum, causing calcium ion release, and muscle contraction. So the correct answer to question is choice E.

Front 33

Cell bodies of primary sensory neurons of mechanoreceptors in the periodontal ligament are found in which of the following brainstem nuclei?
1. Nucleus solitarius
2. Reticular formation
3. Descending nucleus of V
4. Chief sensory nucleus of V
5. Mesencephalic nucleus of V

Back 33

MESENCEPHALIC NUCLEUS OF V

The correct answer is choice 5. The periodontal ligament is the dense fibrous connective tissue which occupies the periodontal space between the root of the tooth and the bone. It consists of a stroma of fibers in a gel of ground substance containing cells, blood vessels and nerve. The periodontal ligament contains mechanoreceptors that may be involved in reflex jaw activity. These receptors are mediated by the trigeminal nerve, cranial nerve V, in association with the mesencephalic nucleus of cranial nerve V in the brainstem. This is choice 5. The nucleus solitarius, choice 1, receives input from the glossopharyngeal nerve, cranial nerve IX, to mediate the gag and carotid reflexes. Reticular formation, choice 2, is a general term used to describe those parts of the brainstem composed of scattered cells intermingling with nerve fibers. Descending nucleus of V, choice 3, and chief sensory nucleus of V, choice 4, are present to confuse the test taker as they are not valid anatomic nuclei. The three sensory nuclei of the trigeminal are the mesencephalic nucleus of V, the principal nucleus of V and the spinal nucleus of V. So the correct answer to question is choice 5.

Front 34

Cell bodies of proprioceptive fibers in V are located in the
A. chief nucleus.
B. spinal nucleus.
C. semilunar ganglion.
D. geniculate ganglion.
E. mesencephalic nucleus.

Back 34

MESENCEPHALIC NUCLEUS
he correct answer is choice E. The mesencephalic nucleus of CN V contains cell bodies of fibers concerned with proprioception. Choice A is incorrect. The chief nucleus of V contains cell bodies for fibers of the motor root of V3. Choice B is incorrect. The spinal nucleus of V contains second-order neurons in the pathway for pain and temperature. Choice C is incorrect. The semilunar ganglion contains sensory cell bodies for all three divisions of CN V. Choice D is incorrect. The geniculate ganglion a contains sensory cell bodies associated with CN VII.

Front 35

Cell bodies of taste fibers from the anterior two-thirds of the tongue are located in which of the following ganglia?
1. Otic
2. Geniculate
3. Submandibular
4. Pterygopalatine
5. Trigeminal (semilunar)

Back 35

GENICULATE

The correct answer is choice 2. Taste from the anterior two-thirds of the tongue is supplied by the chorda tympani, a branch of the seventh nerve or the facial nerve. The cell bodies of these neurons are located in the geniculate ganglia. Choice 1 is incorrect. The otic ganglion contains cell bodies of the lesser superficial petrosal nerve of cranial nerve nine which is secretomotor to the parotid gland. Choice 3 is incorrect. The submandibular ganglion contains cell bodies from neurons of the chorda tympani which are secretomotor to the submandibular gland. Choice 4 is incorrect. The pterygopalatine ganglion contains cell bodies of neurons from the greater superficial petrosal nerve which is secretomotor to the lacrimal, nasal and palatine glands. Choice 5 is incorrect. The trigeminal ganglion contains cell bodies of neurons from the three branches of the uigeminal nerve, cranial nerve five. These do not I supply taste sensation to the anterior two-thirds of the tongue, although the mandibular branch does supply general afferent sensation to the anterior two-thirds. Anyway, the correct answer to question is choice 2.

Front 36

Cell bodies of the somatic motor system lie in which of the following locations?
A. Dorsal horn
B. Ventral horn
C. Autonomic ganglia
D. Dorsal root ganglia
E. lntermediolateral horn

Back 36

VENTRAL HORN

The correct answer is choice B. Giant motor horn cells occupy the ventral horn in the gray matter of the spinal cord. Choice A is incorrect. The dorsal horn contains small central processes of sensory neurons and cell bodies and processes of synaptic cells (interneurons). Choice C is incorrect. Autonomic ganglia are collections of postsynaptic sympathetic or parasympathetic cell bodies. Choice D is incorrect. Dorsal root ganglia are collections of sensory cell bodies. Choice E is incorrect. The intermediolateral horn, or cell column, is a collection of preganglionic autonomic cell bodies.

Front 37

Cells of the stratum granulosum of thick stratified squamous epithelium characteristically contain
1. melanin granules.
2. keratin granules.
3. keratohyalin granules.
4. granules that are organelles.

Back 37

KERATOHYALIN GRANULES

The correct answer is choice 3. The stratum granulosum is a layer of epithelial cells. Let's review the layers briefly. The most undifferentiated basal layer is called the stratum basale. It consists of a single layer of columnar cells. Above this layer is the stratum spinosum or the prickle cell layer. These cells are more flattened and more differentiated than the stratum basale cells. Above the stratum spinosum is the stratum granulosum, flattened cells containing keratohyalin. The outermost layer of cells is the stratum corneum. These cells are dead, flat keratinized cells which flake off the skin or gingiva. So choice 3 is correct. Choice 2, keratin, is found in the stratum corneum. Choice 1, melanin, is found in melanocytes or dendritic cells. These are found in the deepest layer of the epidermis and have processes extending between various adjacent epidermal cells. Choice 4 is incorrect. The keratohyalin granules in the stratum granulosum cells are not organelles. So the correct answer to question is choice 3.

Front 38

Cementum differs from dentin in that cementum
A. contains more inorganic material than dentin.
B. is not formed following eruption of the tooth.
C. can contain cells, whereas dentin contains cells as well as cell processes.
D. is produced by cells of the periodontal ligament, but dentin is produced by pulp cells.
E. contains some elastic fibers, whereas dentin contains only collagenous fibers.

Back 38

IS PRODUCED BY CELLS OF THE PDL, BUT DENTIN IS PRODUCED BY PULPS CELLS.

The correct answer is choice D. Let's review the choices in order. Of the three hard tissues in tooth structure, enamel is most inorganic, followed by dentin, and then cementum. Cementum is histologically most similar to bone. Cementum forms from cementoblasts which become active slightly before, during and after the crown of the tooth has already erupted. Root formation is incomplete when crowns are completely formed and already erupted. Cementum may contain cells(cementocytes in cellular cementum) or not contain cells (acellular cementum). Dentin is considered to be noncellular, as only odontoblastic processes and not whole odontoblasts are found in dentin. Cementoblasts are formed originally in the periodontal ligament, from the dental sac, while odontoblasts form in the pulp (correct choice D). Elastic fibers are not found in any of the three tissues. The inorganic matrix of both dentin and cementum is primarily, but not wholly, collagen. The correct answer to question is choice D.

Front 39

Circular fibers are present in the
1. free gingiva and encircle the tooth.
2. free gingiva and encircle alveolar bone.
3. attached gingiva and encircle alveolar bone.
4. periodontal ligament and encircle the tooth.

Back 39

FREE GINGIVA AND ENCIRCLE THE TOOTH

The correct answer is choice 1. Circular fibers are composed of connective tissue and surround the teeth. These fibers are located in the free gingiva. They do not attach to or encircle the alveolar bone, and are not part of the periodontal ligament. So choices 2, 3 and 4 are all incorrect. Periodontal ligament fibers include the horizontal alveolar crest, oblique and apical fibers. In addition, transseptal periodontal fibers attach from the cementum of one tooth to the cementum of another adjacent tooth. Anyway, the correct answer to question is choice 1.

Front 40

Compared with intertubular dentin, peritubular dentin is characterized by which of the following?
A. Greater stainability
B. Higher quantity of fluids
C. Lesser content of inorganic salts
D. Greater content of inorganic salts
E. Greater content of large collagen fibers

Back 40

GREATER CONTENT OF INORGANIC SALTS

The correct answer is choice D. Peritubular dentin refers to dentin surrounding the odontoblastic process. Intertubular dentin is the remaining dentin found elsewhere. Peritubular dentin is more mineralized and therefore contains both less water and less organic material (collagen, mostly) and stains less darkly. The correct answer to question is choice D.

Front 41

Dentinal tubules are S-shaped in the crown of the tooth due to the
A. incremental pattern.
B. epithelial diaphragm.
C. crowding of odontoblasts.
D. formation of peritubular dentin.
E. calcification pattern of maturing dentin.

Back 41

CROWDING OF ODONTOBLASTS

The correct answer is choice C. Remember that dentin is formed by odontoblasts lining the periphery of the dental pulp, and that as enamel depositon proceeds outward, dentin deposition proceeds inward. As the odontoblasts lay down more and more dentin and near the interior of the dental papilla, they become closer to each other. The curving pattern of the dentin is due to the decreasing amount of space available for the dentinal tubules as they get longer and more interior. A wavy S-shaped pattern results. The correct answer to question is choice C.

Front 42

The capacity of the tongue for forceful movement depends on striated muscle supplied by which of the following cranial nerves?
A. V
B. VII
C. IX
D. X
E. XII

Back 42

The correct answer is choice E, XII.... The hypoglossal nerve is the sole motor nerve of the tongue. Choice A is incorrect. CN V conveys general sensory information via its lingual branch from the anterior two-thirds of the tongue.Choice B is incorrect. CN VII conveys taste from the anterior two-thirds of the tongue via its chorda tympani branch. Choice C is incorrect. CN IX conveys general sensation and taste from the posterior one-third of the tongue.Choice D is incorrect. CN X conveys taste from the portion of the tongue which reflects onto the epiglottis.

Front 43

The cellular organelle that binds and releases calcium during relaxation and contraction of skeletal muscle is the
1. nucleus.
2. lysosome.
3. mitochondrion.
4. transverse tubule.
5. sarcoplasmic reticulum.

Back 43

The correct answer is choice 5, the sarcoplasmic reticulum.... All skeletal muscles are under voluntary control and contract when a signal passes to them from their motor nerve. When activated by this electrical signal, skeletal muscle contraction is initiated by an increase in free calcium ion concentration released by the sarcoplasmic reticulum. When contraction is complete calcium ions are recaptured by the sarcoplasmic reticulum and stored until the next contractile signal is received. The nucleus, choice 1, is the largest organelle in the cell. It contains the majority of the genetic material and is also an essential part of protein synthesis. Lysosomes, choice 2, are membrane-bound organelles in which intracellular digestive enzymes are stored. The mitochondria, choice 3, can be thought of as the powerhouses of the cell. They generate energy by producing ATP in the presence of oxygen. The transverse tubules, choice 4, are found in skeletal muscles in which they carry the electrical signal for the activation of sarcoplasmic reticulum to release calcium to initiate contraction. So the correct answer to question is choice 5.

Front 44

The cerebellar cortex is characterized histologically by which of the following types of cells?
1. Basket
2. Purkinje
3. Pyramidal
4. Martinotti
5. Horizontal

Back 44

The correct answer is choice 2, Purkinje cells.... Cerebellar cortex refers to the outer layers of the cerebellum which is responsible for coordination of muscular contraction and movement. In particular, Purkinje cells of the cerebellar cortex are efferent neurons. However, other inhibitory cells called outer and inner stellate cells or basket cells are also present in the cerebellum. So it appears that choice 1 is also correct. The Purkinje cells are localized in the middle layer of the cerebellar cortex, while the inner and outer stellate cells or basket cells are located in the outer or molecular level. Choice 3 is definitely incorrect. Pyramidal cells refer to the cells of I the cerebellar pyramid which is not on the outer cortex, but moF interior. Choice 4 is incorrect. Martinotti cells are neurons with ascending axon processes found in the polymorphic layer of the cerebral cortex. Choice 5 is incorrect. Horizontal cells are found in the retina and synapse with rods and cones. So the correct answer to question is choice 2.

Front 45

The common bile duct, the hepatic artery and the portal vein are found grouped in the
1. mesocolon.
2. lesser omentum.
3. greater omentum.
4. gastrosplenic ligament

Back 45

the answers to a different question were given. I believe it is the lesser omentum

Front 46

The common hepatic artery is a branch of the
1. gastric artery.
2. splenic artery.
3. celiac artery (trunk).
4. superior mesenteric artery.

Back 46

The correct answer is choice 3, the celiac artery.... The common hepatic artery arises from the celiac trunk and supplies the liver. The celiac trunk is a small branch off the aorta below the level of the diaphragm. It branches into the common hepatic artery which is correct choice 3, the left gastric (choice 1) and the splenic (choice 2). The superior mesenteric artery (choice 4) arises approximately one centimeter below the celiac trunk and supplies the midgut. The right gastric artery (choice 1) arises from the proper hepatic which is a branch of the common hepatic. So our correct answer to question is choice 3. The aorta leads to the celiac trunk which leads to the common hepatic artery.

Front 47

The component of bone tissue that gives bone tensile strength is the
1. elastic fibers.
2. calcified ground substance.
3. interconnecting canaliculi.
4. periosteal connective tissue.
5. collagenous fibrils of matrix.

Back 47

The correct answer is choice 5, collagenous fibrils of matrix... Tensile strength in bone or cartilage is dependent primarily on the number of collagenous fibers present. Choice 1 is incorrect. Elastic fibers will add flexibility and elasticity, but not tensile strength. Choice 2 is incorrect. The calcified ground substance adds compressive strength, not tensile strength. Choice 3 is incorrect. The interconnecting canaliculi serve to interconnect the lacunae which contain osteocytes. They also connect the lacunae to the haversian canal which contains blood vessels. Choice 4 is incorrect. Periosteum covers the bone surface and contains bone-forming osteoblasts, but does not increase tensile strength. So the correct answer to question is choice 5.

Front 48

The connective tissue sheath that surrounds a muscle as a whole and is synonymous with the gross anatomic deep fascia is the
1. epimysium.
2. endomysium.
3. perimysium.
4. periosteum.
5. perichondrium

Back 48

The correct answer is choice 1., epimysium.... The basic unit of skeletal muscle is the muscle cell or fiber. These are grouped together into elongated bundles or fasciculi. The fasciculi are in turn associated in various patterns to form the muscle as a whole. Three different types of connective tissue are found in skeletal muscle. The endomysium, choice 2, a delicate connective tissue surrounds the individual muscle fiber. The perimysium, choice 3, a loose collagenous connective tissue wraps around each fasciculus. The epimysium, choice 1, a dense connective tissue sheath encloses the entire muscle. Periosteum, choice 4, a dense fibrous connective tissue layer covers the external surface of bone. Perichondrium, choice 5, is a zone of condensed connective tissue near the periphery of mature cartilage. So the correct answer to question is choice 1.

Front 49

The core of a cilium is composed of
A. microvilli.
B. microtubules.
C. microfibrils.
D. tonofilaments.
E. microfilaments

Back 49

The correct answer is choice B, microtubules... The cilium, like the flagellum, has a regular structural arrangement of microtubules, which in cross-section appear in a "9+2" arrangement. Nine sets of paired microtubules surround 2 central single microtubules. Microvilli are extensions of intestinal absorptive cell membranes which increase surface area. Microfibrils may refer to muscle cell myofibrils, the smallest contractile units of muscle. These, in turn, are made up of myofilaments of actin or myosin. Tonofilaments are found connecting to desmosomes, which connect some types of epithelial cells. The correct answer to question is choice B.

Front 50

The crescents or demilunes of the mucous alveoli of the sublingual gland are composed of which of the following cells?
A. Mucous
B. Serous
C. Neural
D. Striated
E. Myoepithelial

Back 50

The correct choice is B, serous... No, your eyes are not deceiving you. The answer refers to the fact that mixed glands which are primarily mucous, contain some serous cells as well. The sublingual gland is a good example. The serous cells in this gland are located surrounding alveoli of mucous cells. The group of serous cells forms a crescent or demilune. Striated cells refer to duct epithelial cells which have a striped appearance due to large numbers of mitochondria near their base. Myoepithelial cells (basket cells) form the basal layer of ducts and have a contractile function. The correct answer to question is choice B.

Front 51

The dentist incises the mucous membrane of the floor of the mouth. This incision extends from the molar region to the sublingual caruncle (papilla). Which of the following structural groups will be exposed first?
A. Sublingual gland, lingual nerves, and submandibular duct
B. Hyoglossus and mylohyoid muscles, and hypoglossal nerve
C. Lingual nerve, lingual artery, and anterior belly of the digastric muscle
D. Lingual nerve, hypoglossal nerve, and submental branch of the facial artery
E. Anterior belly of the digastric muscle, mylohyoid nerve, and submental branch of the facial artery

Back 51

The correct answer is choice A, the sublingual gland, lingual nerve, and sublingual duct.....
The sublingual gland, lingual nerve and submandibular duct lie immediately deep to the mucosa of the floor of the mouth. The duct of the submandibular gland crosses the lingual nerve twice, first deeply and then superficially, as it courses to its opening at the sublingual caruncle. Choice B is incorrect. The hypoglossal nerve passes deep to mylohyoid and superifical to hyoglossus as it leaves the anterior triangle to enter the floor of the mouth. Choice 2 is incorrect. The lingual artery enters the tongue by passing deep to hyoglossus. The anterior belly of digastric forms a boundary of the submental triangle, a subdivision of the anterior triangle of the neck. Choice D is incorrect. The submental artery is a branch of the facial artery which travels with the mylohyoid nerve to supply mylohyoid and anterior digastric.

Front 52

The diploid number of chromosomes is maintained in proliferating somatic cells by which of the following processes?
A. Meiosis
B. Mitosis
C. Budding
D. Amitosis
E. Cytokinesis

Back 52

The correct answer is choice B, mitosis.... Mitosis is the division of somatic cells(non-gametes) into other somatic cells. The formation of gametes(sex cells) from somatic cells is called meiosis. In mitosis, chromosome number is conserved, for example in humans the number will remain at 46. In meiosis, or reduction division, the resulting cells will have half the normal chromosome number. In humans this is 23. Budding refers to a type of mitosis used for asexual reproduction by organisms such as yeast. While it is mitotic, it is different from normal mitosis as the cytoplasm is divided unequally, with the bud getting only a small portion. Amitosis means non-mitosis. Cytokinesis is the division of cytoplasm during mitosis. It follows the division of nuclear material. So the correct answer to question is choice B.

Front 53

The esophagus is subdivided into three portions on the basis of a transition in the
1. submucosa.
2. adventitia.
3. mucosal layer.
4. muscularis externa.

Back 53

The correct answer is choice 4, muscularis externa.... The esophagus is a muscular tube, 25cm or 10 inches in length, that conveys food rapidly from the pharynx to the stomach. The esophagus is subdivided into three portions based on its muscularis externa. In the upper third of the esophagus, both the inner and outer layers consist of striated muscles. In the second third, bundles of smooth muscles begin gradually to replace the striated muscle and in the lower third, only smooth muscle is found. The submucosa, choice 1, consists of collagenous and elastic fibers and does not vary throughout the length of the esophagus. The adventitia, choice 2, connects the outer surface of the esophagus with surrounding organs. This layer is made up of loose connective tissue which is also uniform throughout the length of the esophagus. The mucosal layer, choice 3, is also uniform throughout the esophagus. This is the lining layer of the esophagus. So the correct answer to question is choice 4.

Front 54

The external carotid artery contributes to the blood supply of the nasal cavity by way of the
1. facial artery, the superior labial artery and angular arteries.
2. lingual artery, the deep lingual artery and internal nasal arteries.
3. occipital artery, the ascending palatine artery and posterior nasal arteries.
4. maxillary artery, the sphenopalatine artery and posterior lateral nasal arteries.
5. superficial temporal artery, the transverse facial artery and external nasal arteries.

Back 54

The correct answer is choice 4, the maxillary artery, the sphenopalatine artery and posterior lateral nasal arteries.... The external carotid artery, also discussed in another question, supplies the nasal cavity through a variety of branches. The maxillary artery supplies the nasal cavity through branches in the infraorbital, the greater palatine, the sphenopalatine and its branches, and the posterior lateral nasal. So choice 4 is incorrect. Choice 1 is incorrect. The facial artery leads to the superior labial which does supply part of the nasal area, but the angular artery supplies the medial angle of the eye. Choice 2 is incorrect. The lingual artery and deep lingual artery basically supply the tongue with no nasal branches. Choice 3 is incorrect. The occipital artery supplies the area of the base of the head and dorsal neck, or the occipital area. It has no nasal branches. Choice 5 is incorrect. The superficial temporal artery is a terminal branch of the external carotid to the temporal bone area of the head. It has no nasal branches. The transverse facial artery is a branch of the superficial temporal artery, another terminal branch of the external carotid. It also has no nasal branches. The external nasal arteries are branches of the facial artery. So the correct answer to question is choice 4.

Front 55

The foramen ovale is located in the
1. interatrial septum of the adult.
2. interatrial septum of embryo and fetus.
3. interventricular septum of the adult.
4. interventricular septum of embryo and fetus.

Back 55

The correct answer is choice 2, interatrial septum of embryo and fetus... Since the lungs and the fetus are not functioning, various shunts and special structures are present in the fetal circulation to receive oxygenated blood from the placenta. The foramen ovale, an opening between the right and left atrium allows blood from the right atrium to pass directly into the left atrium thereby bypassing the lungs. A similar lung bypass structure in the fetus is the ductus arteriorosis which connects the fetal aorta and the pulmonary artery. So. the correct answer to question is choice 2.

Front 56

The greater peritoneal sac communicates with the lesser peritoneal sac by means of the
1. aortic hiatus.
2. inguinal canal.
3. epiploic foramen.
4. lesser pelvic aperture.
5. superior pelvic aperture

Back 56

The correct answer is choice 3, the epiploic foramen... The peritoneal cavity is divided into two sections: the greater sac and the omental bursa or lesser sac. The omental bursa or lesser sac is an hourglass-shaped area which lies behind the stomach,.the lesser omentum and the caudate lobe of the liver. The greater and lesser sac communicate through the epiploic foramen which is located behind the right border of the lesser omentum. Choice 1 is incorrect. The aortic hiatus or aortic opening in the diaphragm allows the aorta and thoracic duct to pass through the diaphragm. Choice 2 is incorrect. The inguinal canal is the passage in the abdominal wall which transmits the spermatic cord in the male and the round ligament of the uterus in the female, and the ilioinguinal nerve. Choice 4 and 5 are incorrect. The lesser pelvic aperture and superior pelvic aperture refer to spaces or areas within the bony pelvis. So the correct answer to question is choice 3.

Front 57

Desmosomes function by serving as
A. a means for communication between cells.
B. a means for attachment of adjacent cells.
C. an outlet for secretory products of a cell.
D. a bridge for continuity of cytoplasm between adjacent cells.
E. a means by which tonofibrils can pass from one cell into another.

Back 57

A MEANS OF ATTACHMENT OF ADJACENT CELLS.

The correct answer is choice B.
Desmosomes attach adjacent cells to each other, and are known as macula adherens. Tonofilaments from the cytoplasm also terminate in thickened cell membrane located at the desmosome. A nexus, or gap junction, is a site of possible chemical or electrical communication between cells. (Choice A). Choice C is incorrect, as secretory products do not leave through a desmosome. Choice D is incorrect, as cytoplasm of each cell ends at the desmosome, and is distinct from the cytoplasm of adjacent cells. Choice E is incorrect. Tonofibrils from each cell anchor into thickened cell membrane of the same cell, anchoring the cells cytoskeleton. So the correct answer to question is choice B.

Front 58

During an intraoral injection to the mandibular foramen, the needle passes through the mucous membrane and the buccinator muscle. As it does so, the needle lies
A. inferior to the mandibular lingula.
B. superior to the auriculotemporal nerve.
C. lateral to the neck of the mandible.
D. lateral to the medial pterygoid muscle.
E. lateral to the stylomandibular ligament.

Back 58

LATERAL TO THE MEDIAL PTERYGOID MUSCLE

The correct answer is choice D. The medial pterygoid inserts along the inferior portion of the ramus of the mandible. The mandibular foramen is located approximately at the center of the inner surface of the ramus. The inferior alveolar nerve passes lateral to the medial pterygoid as it enters the foramen. Choice A is incorrect. The opening to the mandibular foramen lies at the same level as the lingula. Choice B is incorrect. The auriculotemporal nerve passes posteriorly from the trunk of V3 as it leaves the infratemporal fossa. Choice C is incorrect. The needle approaches the mandibular ramus from its medial, not lateral, aspect. Choice E is incorrect. The stylomandibular ligament is a thickened band of deep cervical fascia which interconnects the angle of the mandible and the styloid process. It is not related to the mandibular foramen.

Front 59

During endochondral ossification of a long bone of an extremity, the function of hyaline cartilage is to
1. increase strength of the developing bone.
2. provide a region where bone can grow in length.
3. provide undifferentiated cells that will become osteoblasts.
4. form cores of trabeculae that compose most compact bone of the diaphysis.

Back 59

PROVIDE A REGION WHERE BONE CAN GROW IN LENGTH

The correct answer is choice 2. In endochondral ossification, the epiphyses or ends of the long bone have areas of actively growing hyalin cartilage. This cartilage produces new cells at the growing end and becomes calcified at the older, nongrowing end, and the calcified cartilage is then replaced by bone. The two ends of the long bone thus grow gradually away from each other. Bone width is increased by a different method in which periosteum lays down new concentric bone layers. The growth in length, due to replacement of cartilage by bone, is known as endochondral ossification. Choice 1 is incorrect. Cartilage is eventually replaced by bone. It does not add strength to it. Choice 3 is incorrect. Osteoblasts do not develop from undifferentiated cartilage cells. Instead, they develop from perichondrial chondrocytes which were present in the cartilage. These chondrocytes are not undifferentiated. Choice 4 is incorrect. The trabeculae are sections of bone formed by osteoblasts and are not formed from cartilage. So the correct answer to question is choice 2.

Front 60

During swallowing, muscular contraction results in movements that seal off the oropharynx from the nasopharynx. Which of the following muscles cause movements that result in a fold in the posterior wall of the pharynx?
A. Levator veli palatini
B. Tensor veli palatini
C. Palatopharyngeus
D. Musculus Uvulae
E. Palatoglossus

Back 60

PALATOPHARYNGEUS

The correct answer is choice C. Palatopharyngeus is one of the three muscles which form the longitudinal muscle layer of the pharynx. The other two are stylopharyngeus and salpingopharyngeus. Choice A is incorrect. Levator veli palatini (levator palati) elevates the soft palate. Choice B is incorrect. Tensor veli palatini (tensor palati) tenses the soft palate. Choice D is incorrect. Musculus uvulae assists in closing the nasopharynx during swallowing. Choice E is incorrect. Palatoglossus elevates the back of the tongue.

Front 61

Each of the following cell types secretes the substance with which it is paired EXCEPT
1. Sertoli's cells-testosterone.
2. corpus luteum-progesterone.
3. alpha cells of the pancreas-glucagon.
4. chromaffin cells of the suprarenal-catecholamine.

Back 61

SERTOLI'S CELL-TESTOSTERONE.

The correct answer is choice 1. Let's review the pairs which are correctly matched first. The corpus luteum, choice 1, in the ovary is formed after the rupture of the graafian follicle. It forms under the influence of luteinizing hormone or LH from the anterior pituitary and secretes progesterone which helps maintain the uterine lining. Choice 2, alpha cells of the pancreas, secrete glucagon, a hormone which raises blood sugar, and is the antagonist of insulin. Insulin is produced by beta cells of the pancreas. Choice 4, chromaffin cells of the suprarenal or adrenal gland produce catecholamines, epinephrine and norepinephrine. These catecholamines are produced by the suprarenal or adrenal medulla. Choice 1 is incorrectly paired and is our correct answer. Testosterone is produced by interstitial cells of the testes. but not by Sertoli cells. Sertoli cells are supporting cells which help nourish developing spermatids. So the correct answer to question is choice 1.

Front 62

Each of the following develops as an outpocketing of the gut tube EXCEPT one. Which one is this EXCEPTION?
A. Lung
B. Liver
C. Spleen
D. Pancreas
E. Gallbladder

Back 62

SPLEEN

The correct answer is choice C. The spleen forms from mesoderm within the layers of the dorsal mesogastrium. Choice A is incorrect. The lungs bud from the ventral aspect of the foregut as the respiratory diverticulum at the junction of pharynx and foregut. Choice B is incorrect. The liver forms as the hepatic diverticulum between the layers of the ventral mesogastrium at the junction of foregut and midgut. Choice D is incorrect. The pancreas arises form dorsal and ventral primordia derived from the gut tube. Choice E is incorrect. The gall bladder develops from an outpocketing of the hepatic diverticulum in the ventral mesogastrium.

Front 63

Each of the following embryologic structures is derived from the first branchial arch EXCEPT one. Which one is this EXCEPTION?
A. Tuberculum impar
B. Maxillary process
C. Mandibular process
D. Intermaxillary process
E. Lateral lingual swelling

Back 63

INTERMAXILLARY PROCESS

The correct answer is choice D. The intermaxillary segment is derived from the fusion of the medial nasal processes, which develop from the frontonasal process. Choice A is incorrect. The tuberculum impar, which participates in the formation of the anterior two-thirds of the tongue, is derived from the first arch. Choice B is incorrect. The maxillary process is part of the first arch. Choice C is incorrect. The mandibular process is part of the first arch. Choice E is incorrect. The lateral lingual swelling is derived from the first arch.

Front 64

Each of the following enters the orbit by way of the superior orbital fissure EXCEPT one. Which one is this EXCEPTION?
A. Abducens nerve
B. Trochlear nerve
C. Oculomotor nerve
D. Ophthalmic artery
E. Ophthalmic division of the trigeminal nerve

Back 64

OPTHALMIC ARTERY

The correct answer is choice D. The ophthalmic artery, together with the optic nerve, enters the orbit by passing through the optic foramen. Choice A is incorrect. The abducens nerve enters the orbit through the superior orbital fissure. Choice B is incorrect. The trochlear nerve enters the orbit through the superior orbital fissure. Choice C is incorrect. The oculomotor nerve enters the orbit through the superior orbital fissure. Choice E is incorrect. The ophthalmic division of the trigeminal enters the orbit through the superior orbital fissure.

Front 65

Each of the following muscles receives motor innervation from the ansa cervicalis EXCEPT one. Which one is this EXCEPTION?
A. Omohyoid
B. Thyrohyoid
C. Geniohyoid
D. Sternohyoid
E. Sternothyroid

Back 65

THYROHYOID AND GENIOHYOID

The correct answer is choice B and choice C. Geniohyoid is supplied by a branch of C1 which travels with CN XII (hypoglossal nerve) and also supplies thyrohyoid. Choice A, Omohyoid, is incorrect. Omohyoid has two bellies, both supplied by ansa cervicalis. Choice D, Sternohyoid, and choice E, Sternothyroid, are both incorrect. They are both innervated by ansa cervicalis, which is a junction of nerves from C1, C2, and C3.

Front 66

Each of the following structures is an opening into the pterygopalatine fossa EXCEPT one. Which one is this EXCEPTION?
A. Facial canal
B. Pterygoid canal
C. Pharyngeal canal
D. Sphenopalatine foramen
E. Pterygomaxillary fissure

Back 66

FACIAL CANAL

The correct answer is choice A. The facial canal opens to the middle cranial fossa as the hiatus of the facial canal. Choice B is incorrect. The pterygoid canal (Vidian canal) conveys the nerve of the same name to the pterygopalatine fossa. It begins in the anterior wall of foramen lacerum at the base of the skull, and passes through the body of the sphenoid bone. Choice C is incorrect. The pharyngeal canal passes from the roof of the nasopharynx to the pterygopalatine fossa. Choice D is incorrect. The sphenopalatine foramen is an opening in the medial wall of the pterygopalatine fossa. It communicates with the nasal cavity. Choice E is incorrect. The pterygomaxillary fissure leads from the infratemporal fossa to the pterygopalatine fossa.

Front 67

The ground substance of hyaline cartilage is basophilic because it contains
1. phosphatases.
2. polypeptides
3. orthophosphoric esters.
4. sulfated proteoglycans.

Back 67

answers were to a different question---- sulfated proteoglycans is correct.

"The ground substance is composed of a mixture of amorphous (non-formed) and fibrous (formed) components. The amorphous component predominantly contains proteoglycans. These consist of polysaccharide chains (glycosaminoglycans) such as keratan sulphate and chondroitin sulphate, which are covalently bound to a protein core. These core proteins are in turn non-covalently bound to a long filament of hyaluronic acid to form large proteoglycan aggregates (Figure 1⇓). Their principle function is to retain water, which is bound to the negatively charged glycosaminoglycans (GAGs), and represents 75% of the total volume of the ground substance. The formed component of the ground substance is composed of collagen fibres that constitute 50% of the dry weight of cartilage. The collagen fibres interact electrostatically with the GAGs to form a cross-linked matrix. The main type of collagen fibre in hyaline cartilage is type II collagen which consists of three alpha-1 (type II) chains [α1(II)]3. This differs from the more common type I collagen, which occurs in skin, tendons and bone, in that it contains higher levels of hydroxylysine and is thus more hydrophilic."

Front 68

The growth rate in the cartilage of the epiphyseal plate of a long bone is markedly retarded when there is a lack of hormone from which of the following?
A. Hypophysis
B. Adrenals
C. Testes
D. Parathyroids
E. Islets of Langerhans

Back 68

The correct answer is choice A, hypophysis....
The hypohysis is the anterior pituitary, and is the source of GH(STH, growth hormone, somatotropic hormone). It stimulates long bone growth at the epiphyseal plate. The adrenal medulla secretes noradrenaline, while the adrenal cortex secretes glucocorticoids and mineralcorticoids (choice B). The testes secrete testosterone (choice C). The parathyroids secrete parathyroid hormone (PTH). The islets of Langerhans of the pancreas secrete insulin and glucagon (choice E). None of these hormones have a direct influence on bone growth at the epiphyseal plate. The correct answer to question is choice A.

Front 69

The hepatic veins drain blood from the liver into the
A. inferior vena cava.
B. superior vena cava.
C. azygos vein.
D. portal vein.
E. superior mesenteric vein.

Back 69

The correct answer is choice A, the inferior vena cava... Two or three hepatic veins drain from the liver to the inferior vena cava as it passes through the diaphragm to enter the right atrium of the heart. Choice B is incorrect. The superior vena cava returns blood from the head, neck and upper limbs to the right atrium of the heart. Choice C is incorrect. The azygos system drains blood from the veins of the posterior abdominal wall and posterior thoracic wall to the superior vena cava. Choice D is incorrect. The portal vein transports blood from the GI system and spleen to the liver. Choice E is incorrect. The superior mesenteric vein is a major tributary of the portal vein, which transports blood from the GI system and spleen to the liver.

Front 70

The hypophysis is situated in a fossa of which of the following bones?
A. Ethmoid
B. Frontal
C. Temporal
D. Sphenoid
E. Palatine

Back 70

The correct answer is choice D, sphenoid... The hypophysis rests in a depression in the body of the sphenoid bone known as the hypophyseal fossa. The body of the sphenoid bone is also known as the sella turcica. It forms the midportion of the middle cranial fossa. Choice A is incorrect. The ethmoid bone contributes to the floor of the anterior cranial fossa, in the form of the crista galli and cribriform plate. Choice B is incorrect. The orbital plate of the frontal bone forms much of the floor of the anterior cranial fossa. Choice C is incorrect. The petrous portion of the temporal bone forms the postero-lateral aspect of the middle cranial fossa. Choice E is incorrect. The palatine bone does not contribute to the floor of the cranial cavity.

Front 71

The impulse-conducting mechanism in the heart is composed of
1. autonomic nerve fibers.
2. bundles of collagenous fibers.
3. reticuloendothelial components.
4. modified cardiac muscle fibers.

Back 71

The correct answer is choice 4, modified cardiac muscle fibers.... The conducting tissue of the heart or Purkinje fibers are specialized cardiac musclc cells which spread out throughout the heart and speed conduction. They are structurally different on the cellular level from normal contracting cardiac muscle fibers. Choice 1 is incorrect. Autonomic nerve fibers may control the heart rate through sympathetic and parasympathetic stimulation; however, they do not conduct the contraction impulse. Choice 2 is incorrect as collagenous fibers would be unlikely to have impulse-conducting abilities. Choice 3 is incorrect. Reticuloendothelial components refers to the tissue macrophage system and are part of the immune system. So the correct answer to question is choice 4.

Front 72

The infrahyoid muscles receive their motor innervation from which of the following?
A. Vagus nerve
B. Supraclavicular nerves
C. Brachial plexus
D. Pharyngeal plexus
E. Branches of the cervical plexus

Back 72

The correct answer is choice E, branches of the cervical plexus.... The infrahyoid (strap) muscles receive their innervation from ansa cervicalis, with the exception of thyrohyoid, which is supplied by a branch of cervical nerve I which also supplies geniohyoid. Choice A is incorrect. The vagus supplies muscles of the pharynx and larynx. It does not supply the infrahyoid muscles. Choice B is incorrect. Supraclavicular nerves are cutaneous branches of cervical plexus derived from c3 and c4. They form three sets of branches (medial, intermediate, lateral) which supply the skin over the clavicle. Choice C is incorrect. The brachial plexus is derived from the lower four cervical nerves and the first thoracic nerve. It supplies muscles of the shoulder and axillary regions, and of the upper limb. Choice D is incorrect. Pharyngeal plexus consists of pharyngeal branches of CN's IX, X and the cranial poriton of XI. It supplies muscles of the pharynx and - soft palate.

Front 73

The jugular foramen transmits which cranial nerves?
1. VII, IX, and XII
2. IX, X, and XI
3. IX, XI, and XII
4. X, XI, and XII

Back 73

The correct answer is choice 2, IX, X, and XI... The jugular foramen is an irregular foramen situated lateral to the occipital condyle. It transmits the internal jugular vein, the glossopharyngeal nerve (cranial nerve IX), the vagus nerve (cranial nerve X) and the spinal accessory nerve (cranial nerve XI). So the correct answer to question is choice 2. Note that the questions of this nature are very straightforward and appear often on the boards. Review all the major foramina of the skull and the structures that pass through them in your review notes

Front 74

The junction between primary and secondary dentin is characterized by a
1. resting line.
2. reversal line.
3. sharp reduction in number of dentinal tubules.
4. sharp change in direction of dentinal tubules.
5. Both 1 and 3 above

Back 74

The correct answer is choice 4, sharp change in direction of the dentinal tubules... Secondary dentin can be found just interior to primary dentin, narrowing and enclosing the pulpal tissue. When primary dentin borders on secondary dentin, the tubules abruptly change direction although their number is approximately the same. So choice 3 is incorrect. Choices 1 and 2 are also incorrect. Resting lines and reversal lines are lines present in bone remodeling and not in primary and secondary dentin. Reversal lines show where resorption ends and deposition begins and are scalloped. Arrest lines are highly calcified straight lines between layers of bone. Both types of lines are highly basophilic. So the correct answer to question is choice 4.

Front 75

The lamina papyracea is located in the orbital
1. roof.
2. floor.
3. lateral wall.
4. medial wall

Back 75

The correct answer is choice 4, medial wall.... The orbit consists of a roof, floor, medial and lateral walls. The roof is formed primarily by the orbital part of the frontal bone and also by the lesser wing of the sphenoid, The lateral wall is formed by the greater wing of the sphenoid, the zygomatic and the frontal bone. The medial wall is formed primarily by the frontal process of the maxilla, the maxillary process of the frontal bone, the small thin lacrimal bone, and the ethmoid bone. A thin section of the ethmoid bone, about the thickness of a sheet of paper, is known as the lamina papyracea. So the correct answer is choice 4. The only other choice we haven't mentioned is choice 2, the floor of the orbit, and that is formed by the orbital surface of the maxilla, the zygomatic bone, and the orbital process of the palatine bone.

Front 76

The large ascending bundle of fibers in the medulla that is composed of second order neuron fibers conveying proprioception and discriminatory touch sensations to conscious levels is the
1. medial lemniscus.
2. reticular formation.
3. spinal trigeminal tract.
4. inferior cerebellar peduncle.

Back 76

The correct answer is choice 1, medial lemniscus..... The medial lemniscus is an ascending fiber tract in the medulla and carries proprioceptive and touch sensation. Choice 2 is incorrect. The reticular formation is also in the medulla and contains both afferent and efferent fibers. Many of them connect to areas of the cerebellum, thalamus, corpus striatum and cerebral cortex. Choice 3 is incorrect. The spinal trigeminal tract is located in the lateral aspect of the medulla and carries painful and thermal sensations. Choice 4 is also incorrect. The inferior cerebellar peduncle connects the cerebellum to the medulla, and carries proprioceptive information back and forth from the cerebellum to the medulla. It does not reach the conscious levels of the cerebrum. So the correct answer to question is choice 1.

Front 77

The large mass of gray matter that bulges into the floor and the lateral aspect of the lateral ventricle is the
1. hypothalamus.
2. caudate nucleus.
3. substantia nigra.
4. amygdaloid complex

Back 77

The correct answer is choice 2, caudate nucleus.... The caudate nucleus is a comma-shaped section of the cerebrum and is located just inferiorly and laterally to the lateral ventricle of the brain. The hypothalamus, choice 1, is located far inferior to this area, below the thalamus and third ventricle. Among other functions, the hypothalamus produces hormone-releasing factors and controls temperature, hunger and thirst and other basic functions. Choice 3, the substantia nigra, is a large nucleus deep in the base of the cerebrum below the thalamus and too inferior to be the correct answer. Reduced dopamine production in the substantia nigra is associated with Parkinson's disease. Choice 4 is also incorrect. The amygdaloid complex is located within the tail of the caudate nucleus. Its function is not clearly known and it is located near the anterior portion of the lateral ventricle. So the correct answer to question is choice 2.

Front 78

The lateral boundary of the retropharyngeal space at the level of the oropharynx is the
1. carotid sheath.
2. pterygomandibular raphe.
3. medial pterygoid muscle and its fascia.
4. stylopharyngeus muscle and its fascia

Back 78

The correct answer is choice 1, carotid sheath.... The retropharyngeal space is an area anterior to the cervical vertebrae and composed of loose areolar tissue. It is bordered laterally by the carotid sheath with the contained vessels, including the carotid artery, internal jugular vein and vagus nerve. Choice 2, the pterygomandibular raphe, is a fibrous line to which the buccinator and superior constrictor of the pharynx attach. Choices 3 and 4 are incorrect. The medial pterygoid is a primary closing or elevating muscle which attaches to the mandible, the pterygoid plate and the palatine bone. The stylopharyngeus attaches to the styloid process, the wall of the pharynx and the thyroid cartilage. So anyway, the correct answer to question is choice 1.

Front 79

The lateral pterygoid muscle inserts into which of the following?
A. Condylar process only
B. Medial aspect of the mandibular ramus
C. Articular disk of the temporomandibular joint only
D. Articular disk of the temporomandibular joint and neck of the mandible
E. Articular disk of the temporomandibular joint and coronoid process

Back 79

The correct answer is choice D, articular disk of the TMJ and neck of the mandible..... Most of the fibers of lateral pterygoid insert into the fovea, a pit-like depression on the neck of the mandible. In most individuals, some fibers insert directly into the disk as well. Choice A is incorrect. Fibers of the lateral pterygoid insert specifically into the fovea of the neck of the mandible, and the articular disk (meniscus), which is not part of the condylar process. Choice B is incorrect. The medial pterygoid inserts along the medial aspect of the mandibular ramus. Choice C is incorrect. The majority of fibers of the lateral pterygoid do not insert into the disk. Choice E is incorrect. The temporalis inserts on the coronoid process of the mandible.

Front 80

The left recurrent laryngeal nerve is closely related at its beginning to the
A. left subclavian artery.
B. arch of the aorta and the left pulmonary veins.
C. ligamentum arteriosum and the arch of the aorta.
D. pulmonary trunk and the left brachiocephalic vein.
E. ligamentum arteriosum and the left brachiocephalic vein.

Back 80

The correct answer is choice C, ligamentum arteriosum and the arch of the aorta.... The left recurrent laryngeal nerve recurs in the mediastinum, around the ligamentum arteriosum and arch of the aorta. Choice A is incorrect. The left recurrent laryngeal nerve is not associated with the left subclavian artery. The right recurrent laryngeal nerve, however, recurs around the right subclavian artery in the root of the neck. Choice B is incorrect. The recurrent laryngeal nerves do not contact the pulmonary veins. Choice D is incorrect. The recurrent laryngeal nerves ascend to the larynx by travelling between the trachea and esophagus, and do not contact the pulomonary trunk or brachiocephalic veins. Choice E is incorrect. The left recurrent laryngeal nerve does not contact the left brachiocephalic vein.

Front 81

The lingula of the mandible serves as an attachment for which of the following?
A. Temporalis
B. Stylomandibular ligament
C. Sphenomandibular ligament
D. Temporomandibular ligament
E. Tendon of the digastric muscle

Back 81

The correct answer is choice C, the sphenomandibular ligament.... The sphenomandibular ligament extends from the spine of the sphenoid bone to the lingula of the mandible. Choice A is incorrect. The temporalis inserts on the coronoid process of the mandible. Choice B is incorrect. The stylomandibular ligament extends from the angle of the mandible to the styloid process. Choice D is incorrect. The temporomandibular ligament attaches to the neck of the mandible. Choice E is incorrect. The intermediate tendon of the digastric muscle attaches to the hyoid bone.

Front 82

Each of the following structures is bound by a membrane EXCEPT one. Which one is this EXCEPTION?
A. Nucleolus
B. Lysosome
C. Nucleus
D. Mitochondrion
E. Pinocytotic vesicle

Back 82

NUCLEOLUS

The correct answer is choice A. The nucleolus is a darkly staining section of the nucleus, rich in RNA, in particular ribosomal RNA. It is not separated from the rest of the nucleus by a membrane. The lysosome is a single layer membrane-enclosed organelle containing various hydrolytic enzymes. The nucleus is separated from the cytoplasm by a double membrane, with many pores, known as the nuclear membrane. The mitochondrion, site of ATP synthesis, is also enclosed by a double layered membrane. Pinocytotic vessicles are formed as the plasma membrane(cell membrane) encloses material surrounding the cell and forms a vacuole (pinocytotic vessicle) around it. It is therefore surrounded by a single layered membrane. The correct answer to question is choice A.

Front 83

Each of the following structures lies between the hyoglossus and the mylohyoid muscles EXCEPT one. Which one is this EXCEPTION?
A. Lingual nerve
B. Lingual artery
C. Sublingual gland
D. Submandibular duct
E. Hypoglossal nerve

Back 83

LINGUAL ARTERY

The correct answer is choice B. The lingual artery passes deep to both mylohyoid and hyoglossus to enter the tongue. Choice A is incorrect. The lingual nerve enters the floor of the mouth between mylohyoid and hyoglossus to lie superficially under the mucosa. Choice C is incorrect. The sublingual gland lies immediately under the mucosa of the floor of the mouth. Choice D is incorrect. The submandibular duct crosses the lingual nerve twice as it passes toward the sublingual caruncle at the anterior aspect of I the sublingual gland. Choice E is incorrect. The hypoglossal nerve passes between mylohyoid and hyoglossus as it leaves the anterior triangle to enter the tongue.

Front 84

Enamel spindles are formed by
1. cracks.
2. ameloblasts.
3. hypoplastic rods.
4. hypocalcified rods.

Back 84

HYPOPLASTIC RODS
The correct answer is choice 3. Enamel spindles are formed from odontoblastic processes which project into the enamel and probably originally projected into the ameloblast layer. They are at right angles to the DEJ and may be responsible for sensitivity shown by patients as excavation nears the DEJ. Choice 1 is incorrect. Enamel lamellae, which are not related to spindles, appear to be naturally occurring cracks or cleavages in enamel. Choice 2 is incorrect. Ameloblasts form enamel and move away from the area of the DEJ as enamel is formed. Choices 4 and 5 are incorrect as enamel spindles are not related to enamel rods which are the mineralized structural components of enamel. So the correct answer to question is choice 3.

Front 85

Enlargement of the third ventricle and both lateral ventricles is caused by obstruction of the
A. cerebral aqueduct.
B. foramen of Magendie.
C. foramina of Luschka.
D. interventricular foramina of Monro.

Back 85

CEREBRAL AQUEDUCT

The correct answer is choice A. Obstruction of the cerebral aqueduct is the only blockage that will affect the lateral and third ventricles exclusively. Choice B is incorrect. Obstruction of the foramen of Magendie, in the roof of the fourth ventricle, will cause enlargement of the fourth ventricle as well as the other three. Choice C is incorrect. Obstruction of the foramina of Luschka in the fourth ventricle will cause enlargement of the entire ventricular system. Choice D is incorrect. Obstruction of the interventricular a foramina will cause enlargement of only the lateral ventricles.

Front 86

Fordyce spots appearing on the mucous membrane of the cheek result from the presence of
1. aberrant sweat glands.
2. aberrant sebaceous glands.
3. superficial salivary glands.
4. aberrant fatty accumulations.
5. none of these.

Back 86

ABERRANT SEBACEOUS GLANDS

The correct answer is choice 2. Fordyce spots manifest most frequently as small yellow spots in a bilaterally symmetrical pattern on the cheek mucosa. Fordyce spots are considered a developmental anomaly. They are characterized by heterotopic collections of sebaceous glands at various sites in the oral cavity. It has been postulated that the occurrence of sebaceous glands in the mouth may result from inclusion of ectoderm having potentialities of skin during embryonic development of the maxillary and mandibular processes. The remaining choices do not describe origins of Fordyce spots. So the correct answer to question is choice 2.

Front 87

From an anatomic standpoint, an emergency airway may be established most readily by opening into the trachea
1. between thyroid cartilages.
2. at the level of the jugular notch.
3. through the thyrohyoid membrane.
4. through the median cricothyroid ligament.

Back 87

THROUGH THE MEDIAN CRICOTHYROID LIGAMENT

The correct answer is choice 4. The preferred location of an emergency airway is between the thyroid cartilage and cricoid cartilage in a ligamentous area known as the cricothyroid ligament. It is easier to pass an instrument through this connective tissue than through nearby hard tissue areas. Choice 1 is incorrect. The two thyroid cartilages are fused in the anterior midline. Choice 2 is incorrect. Jugular notches exist in the temporal and occipital bones and in the sternum. How they relate to this question is unclear. Choice 3 is incorrect. The thyrohyoid membrane runs from the hyoid bone to the thyroid cartilage. This area lies above the thyroid cartilage and is not used as an area for establishing airways. So the correct answer to question is choice 4.

Front 88

From which of the following is the periodontal ligament derived?
A. Dental sac
B. Enamel organ
C. Dental papilla
D. Epithelial root sheath
E. Outer enamel epithelium

Back 88

DENTAL SAC

The correct answer is choice A. Briefly, the dental sac forms the periodontal ligament and, indirectly, the cementum, while the enamel organ produces, of course, enamel. The dental papilla produces pulp, and indirectly, the dentin. The epithelial root sheath forms the outline of the root, and induces the odontoblasts of the root to lay down the first layer of root dentin. Outside of this layer, it forms the periodontal ligament and from there cementoblasts will form the cementum of the tooth. The outer enamel epithelium, with the inner enamel epithelium and stellate reticulum form the enamel organ. The correct answer to question is choice A.

Front 89

Gingiva is different from alveolar mucosa in that gingiva has
1. elastic fibers.
2. simple epithelium.
3. muscularis mucosa.
4. stratified epithelium.
5. high connective tissue papillae.

Back 89

HIGH CONNECTIVE TISSUE PAPILLAE

The correct answer is choice 5. Let's review the choices. Gingiva differs from alveolar mucosa in the types of fibers present. Gingiva contains collagenous fibers only, while alveolar or lining mucosa contains both collagenous and elastic fibers. So choice 1 is opposite and incorrect. Alveolar mucosa and gingiva do not differ in this way because both gingiva and alveolar mucosa are stratified epithelium, not simple. Choice 3 is incorrect. The submucosa of gingival tissue contains many collagen fibers, but not muscle or elastic fibers, while the submucosa of alveolar or lining mucosa contains collagenous, elastic and muscle fibers. So choice 3 is opposite and incorrect. Choice 5 is correct. Connective tissue papillae extend into the gingiva to a much greater degree than they do into the alveolar mucosa. Rete pegs which are epithelial extensions into the submucosal tissue are also more prominent in gingival tissue than in alveolar mucosa. So the correct answer to question is choice 5.

Front 90

Hertwig's epithelial root sheath is derived from which of the following?
A. Inner dental epithelium and stellate reticulum
B. Inner dental epithelium and stratum intermedium
C. Outer dental epithelium and stellate reticulum
D. Outer dental epithelium and stratum intermedium
E. Inner dental epithelium and outer dental epithelium

Back 90

INNER AND OUT DENTAL EPITHELIUM

The correct answer is choice E. At the cervical end of the crown, the inner and outer enamel epithelia come together and the stellate reticulum is lost. The joined layers are now called the epithelial root sheath of Hertwig. It induces the tissue nearby to form odontoblasts for root dentin, which in turn induces exterior cells nearby to form into cementoblasts, and produce cementum. Note that the stratum intermedium is a thin layer of cells between the inner enamel epithelium and the stellate reticulum. Its function is unclear. The correct answer to question is choice E.

Front 91

Highly skilled, discrete motor activity of the hand is dependent on which of the following cortical areas of the hemisphere?
A. Transverse temporal gyrus
B. Angular gyrus of the parietal lobe
C. Precentral gyrus of the frontal lobe
D. Paracentral lobule on the medial surface

Back 91

PRECENTRAL GYRUS OF THE FRONTAL LOBE

The correct answer is choice C. The precentral gyrus of the frontal lobe is the "motor strip" from which voluntary motor activity originates. Choice A is incorrect. The transverse temporal gyrus is an auditory area. Choice B is incorrect. The angular gyrus of the parietal lobe is a sensory language area in the dominant hemisphere. Choice D is incorrect. The paracentral lobule is the portion of the motor strip which reflects onto the medial surface of the frontal lobe. It is concerned with movement of the distal lower extremity.

Front 92

Histologically, the osteoclasts of bone resorption are typically
A. anuclear
B. mononuclear.
C. multinuclear.
D. polymorphonuclear

Back 92

MULTINUCLEAR

The correct answer is choice C. Osteoclasts are bone resorbing cells which are are involved in calcium equillibrium, bone remodeling, and bone maintenance. They are stimulated by parathyroid hormone. They have an unusual appearance, with many nuclei (multinuclear). Anuclear, choice A, refers to lack of a nucleus(ex:erythrocyte). Mononuclear, choice B, refers to one nucleus (most cells). Polymorphonuclear, choice D, refers to cells of the same type having nuclei of various shapes, but only one per cell.(ex: neutrophils or polymorphonucleocytes). The correct answer to question is choice C.

Front 93

How many lobes does the right lung usually have?
A. 1
B. 2
C. 3
D. 4
E. 5

Back 93

3

The correct answer is choice C. The right lung has three lobes: superior, middle, and inferior. Choice A is incorrect. Choice B is incorrect. The left lung has two lobes: superior and inferior. Choice D is incorrect. Choice E is incorrect.

Front 94

Hyaline cartilage differs from bone in that hyaline cartilage
1. cells lie in lacunae.
2. may grow interstitially.
3. may grow appositionally.
4. can become more highly calcified.

Back 94

MAY GROW INTERSTITIALLY

The correct answer is choice 2. Hyalin cartilage is a support tissue which may later be replaced by bone or may persist throughout life. In cartilage, cells called chondrocytes are found in spaces called lacunae. However, this does not differ from bone where osteocytes can also be found in lacunae, so choice 1 is incorrect. Choice 2 is our correct answer. Cartilage may grow interstitially, which means growth from within the interior of the tissue up to a certain size beyond which the chondrocytes will die, being too far from vascular supply. Bone cannot grow interstitially as osteocytes are locked into their calcified lacunae. Bones grow at their ends rather than throughout their interior. This growth at the ends is known as appositional growth. So while cartilage can undergo both types of growth. bone can only grow appositionally. Choice 3 is therefore incorrect as they both can grow appositionally. Choice 4 is incorrect. Hyaline cartilage generally does not calcify and become bone. Rather, it calcifies and is replaced by bone in a process known as ossification. However, cartilage does not ever become more highly calcified than bone. So the correct answer to question is choice 2.

Front 95

If the facial nerve were to be cut just after it exited the stylomastoid foramen, it would cause loss of innervation to which of the following?
A. Lacrimal gland
B. Mylohyoid muscle
C. Submandibular gland
D. Oribicularis oculi muscle
E. Anterior belly of the digastric muscle

Back 95

ORIBICULARIS OCULI

The correct answer is choice D. The motor root of the facial nerve enters the parotid gland, where it branches to supply the muscles of facial expression. Choice A is incorrect. The branch of CN VII which supplies the lacrimal gland is the greater superficial petrosal nerve. It is given off inside the petrous portion of the temporal bone, where it runs in the facial canal. Choice B is incorrect. The nerve to mylohyoid is a branch of the inferior alveolar nerve, a branch of CN V3. Choice C is incorrect. The parasympathetic fibers to the submandibular ganglion and gland travel in the chorda tympani, a branch of CN VII which leaves the motor root in the middle ear cavity. Choice E is incorrect. Anterior belly of digastric is supplied by the branch of CN V3 which innervates mylohyoid.

Front 96

If the spinal tract of the fifth cranial nerve were sectioned at the level of the caudal medulla, which of the following modalities would be most affected?
1. Taste
2. Proprioception
3. Pain from the ipsilateral side of the face
4. Light touch from the contralateral side of the face

Back 96

PAIN FROM IPSILATERAL SIDE OF THE FACE

The correct answer is choice 3. The fifth cranial nerve or trigeminal nerve has many functions, including motor, sensory and parasympathetic. It is sensory to all areas of the face through its branches: the ophthalmic V1, the maxillary V2, and the mandibular V3. Sensation is carried to the ipsilateral or same side of the brain as the sensation is received on. Choice 4 is therefore incorrect. The trigeminal nerve would be the afferent nerve for light touch, but the sensations do not cross to the contralateral side of the brain. B Choice 2 is incorrect. Some proprioception from the TMJ and muscles of mastication is related to the trigeminal nerve, but other proprioceptive information from the facial muscles is transmitted by the facial nerve, cranial nerve 7. Choice 1 is incorrect. Taste from the anterior two-thirds of the tongue is transmitted by the facial nerve. The taste sensation from the posterior one-third of the B tongue is transmitted by the glossopharyngeal nerve, cranial nerve 9. So the correct answer to question is choice 3.

Front 97

In a faciolingual section through a tooth and its related gingiva, the demarcation line between free gingiva and attached gingiva extends between the
1. alveolar crest and the free gingival groove.
2. bottom of the gingival sulcus and the free gingival groove.
3. apical margin of the epithelial attachment and the alveolar crest.
4. apical margin of the epithelial attachment and the free gingival groove.

Back 97

BOTTOM OF THE GINGIVAL SULCUS AND THE FREE GINGIVAL GROOVE

The correct answer is choice 2. The gingiva may be subdivided into the attached gingiva and the free gingiva. The attached gingiva is firmly bound to the periosteum of the alveolus and to the teeth. The free gingiva lies unattached around the cervical margin of the tooth. These two regions are distinctly demarcated by the free gingival groove. When viewed from a facial lingual section, the division line between the attached and free gingiva extends between the bottom of the gingival sulcus and the free gingival groove. So the correct answer to question is choice 2.

Front 98

In a newly erupted tooth, the junction between tooth surface and the crevicular epithelium consists of which of the following?
A. Interstitial crevicular fluid
B. Basal lamina-like structure between enamel and epithelium
C. Basal lamina-like structure between cementum and epithelium
D. Basal lamina-like structure between dentin and epithelium
E. Keratin fibers, running from the epithelium deeply into the enamel

Back 98

BASAL LAMINA LIKE STRUCTURE BETWEEN ENAMEL AND EPITHELIUM

The correct answer is choice B. When the crown of the tooth is fully formed, eruption begins. The root continues to form. The remnants of the enamel organ, now known as reduced enamel epithelium, join with the oral mucosal epithelium above the emerging crown. The crown pushes through this combined tissue, which is now termed the junctional epithelium. This junctional epithelium can form hemi- desmosomes and a basal lamina-like structure between the epithelium and adjacent enamel at the CEJ. This is the basal lamina-like structure referred to in the question. Note that this structure only exists between enamel and epithelium as neither the root dentin nor root cementum is fully formed, and only enamel of the crown contacts the reduced enamel epithelium and mucosa on the way up. Also note that at no time is enamel pierced deeply by any fibers from the exterior. Only cementum contains fibers of the PDL. The correct answer to question is choice B.

Front 99

In a relaxed state, transitional epithelium can be distinguished from stratified squamous epithelium because transitional epithelium contains
1. stratum corneum.
2. flattened superficial cells.
3. dome-shaped superficial cells.
4. more visible ground substance.

Back 99

DOME-SHAPED SUPERFICIAL CELLS

The correct answer is choice 3. Transitional epithelium is present only in the urinary bladder and ureters. Transitional epithelium, unlike most epithelial tissue, is capable of expansion. The dome-shaped superficial cells, choice 3, can flatten when the bladder is distended with urine, thus. in effect, stretching the bladder. Choice 1 is incorrect. The stratum corneum is the superficial keratinized layer of stratified squamous epithelium, not transitional epithelium. Choice 2 is incorrect. The transitional epithelium becomes flattened when the bladder is in the expanded state, not in the relaxed state. Choice 4 is incorrect. Ground substance usually refers to material secreted by cells, such as the ground substance secreted by chondrocytes in cartilage. Its relationship to this question is unclear. So the correct answer to question is choice 3.

Front 100

In a routine demineralized histologic section of an adult tooth, the area representing enamel is generally optically clear because
1. enamel is very poor in organic matrix.
2. enamel is very brittle and breaks off during sectioning.
3. ordinary stains do not stain the organic matrix of enamel
4. the mounting medium has the same refractive index as enamel.

Back 100

ENAMEL IS VERY POOR IN ORGANIC MATRIX

The correct answer is choice 1. When demineralized sections of teeth are made, the mineral is removed and the organic matrix remains. Enamel, being approximately 95% mineral and approximately 4% water, will leave behind very little structure when demineralized and so will appear empty and clear to light. Choice 2 is incorrect as teeth are demineralized first before histologic sectioning. Choice 3 is incorrect. Stains will stain the organic matrix, but very little matrix exists. Choice 4 is incorrect. Whether or not the mounting medium has the same refractive index as the enamel or not is irrelevant, as 99% of the enamel is not there when you look at the histologic slide. So the correct answer to question is choice 1.

Front 101

In salivary glands, folds of the basal portion of the cell membrane containing mitochondria are characteristic of the
1. cells composing demilunes.
2. cells of the striated ducts.
3. cells of the intercalated ducts.
4. serous cells of the parotid gland.

Back 101

CELLS OF THE STRIATED DUCTS

The correct answer is choice 2. Striated duct cells have specialized basal portions which contain numerous mitochondria. These striated duct cells are specialized for ion transport and exchange ions in such a way that saliva has a predictable ionic composition. The mitochondria supply energy for active transport of ions. Choice 1 is incorrect. Serous demilune cells produce serous and mucous secretion, but do not accomplish the ion exchange just mentioned for the striated ducts. The demilunes are located in the submaxillary gland. Choice 3 is incorrect. The intercalated ducts cany the mucous or serous secretions from the acini where they are produced to the striated ducts where the ion content is adjusted. Choice 4, serous cells of the parotid gland, is also incorrect. The serous cells produce serous secretion which is later adjusted by the ion exchange in the striated duct. So the correct answer to question is choice 2.

Front 102

In terms of wall thickness, the relative proportion of smooth muscle is GREATEST in which of the following?
A. Veins
B. Venules
C. Arterioles
D. Capillaries
E. Large arteries

Back 102

ARTERIOLES

The correct answer is choice C. We should only consider choices C and E in our answers. In general, arteries have thicker smooth muscle layers(tunica media) than veins, due to the necessity of having to resist high pressures during systole. Capillaries have no smooth muscle layer at all, consisting of endothelial cells only. If we cross section both the large artery and arteriole, we find that, relative to its size, the arteriole contains a greater proportion of muscle tissue compared to the large artery, even though both are muscular. This is due to the fact that the tunica adventitia (outer layer) and tunica intima (inner layer) of the arterioles are often relatively thin. The correct answer to question is C.

Front 103

In the circulating blood of an adult, which of the following leukocytes normally appears in the highest numbers?
1. Basophils
2. Monocytes
3. Eosinophils
4. Neutrophils
5. Lymphocytes

Back 103

NEUTROPHILS

The correct answer is choice 4. Leukocytes, or white blood cells, are made up of five cell types which are subdivided into two main classes, the granulocytes and the agranulocytes. The granulocytes consist of neutrophils, eosinophils and basophils. The agranulocytes consist of lymphocytes and monocytes. Neutrophils, choice 4, of the granulocyte class are the most common type of leukocytes in blood. They constitute from 55-65% of total circulating leukocytes. This is followed by lymphocytes, choice 5, monocytes. choice 2, eosinophils, choice 3, and the rarest leukocyte, the basophil. choice 1. So the correct answer to question is choice 4.

Front 104

In the developing embryo the palate is separated from the lip by a shallow sulcus in the depths of which two epithelial laminae arise. The outer lamina is the
A. dental lamina for primary teeth.
B. dental lamina for permanent teeth.
C. primordium of the parotid gland.
D. primordium of the buccal frenula.
E. vestibular lamina.

Back 104

VESTIBULAR LAMINA

The correct answer is choice E. The first sign of tooth development is the formation of two thickenings, known as the primary epithelial bands, on each developing arch. The outer band eventually becomes the vestibular lamina, while the inner band becomes the dental lamina. The vestibular lamina indents and forms a furrow which separates the lips and cheeks from the alveolar processes. The dental lamina eventually forms the tooth buds (20 buds for the primary teeth). The correct answer to question is choice E.

Front 105

In the fetal heart, the foramen ovale connects the
1. pulmonary artery and the aorta.
2. right and the left atria, permitting the flow of blood from right to left.
3. right and the left atria, permitting the flow of blood from left to right.
4. right and the left ventricles, permitting the flow of blood from right to left.
5. right and the left ventricles, permitting the flow of blood from left to right.

Back 105

RIGHT AND THE LEFT ATRIA, PERMITTING FLOW OF BLOOD FROM RIGHT TO LEFT

The correct answer is choice 2. The foramen ovale is a right-to-left shunt in the fetal heart connecting the two atria. Blood from the umbilical vein returns from oxygenation in the placenta and enters the fetus. Most of the oxygenated blood bypasses the liver through another fetal structure, the ductus venosus. It enters the vena cava and returns to the right atrium. Since the lungs are nonfunctioning in the fetus, the bulk of the blood is not pumped through the pulmonary system. but instead crosses to the left atrium and then to the left ventricle and aorta. So the correct answer to question is choice 2. Choice 1 refers to the ductus aneriosus, another pulmonary system bypass where blood in the pulmonary artery will bypass the lungs by traveling through the ductus arteriosus into the aorta. Anyway, the correct answer to question then is choice 2.

Front 106

In the fetus, blood enters the common carotid arteries by means of the
1. aorta.
2. pulmonary vein.
3. pulmonary artery.
4. ductus arteriosus.
5. thebesian veins (venae cordis minimae).

Back 106

AORTA

The correct answer is choice 1. In the fetus as in the adult, the common carotid arteries branch from the aorta. The left common carotid branches from the aortic arch and the right common carotid from the innominate or brachiocephalic artery which branches from the aortic arch. Choices 2 and 3 are incorrect. The pulmonary system in the fetus is mostly nonfunctional, with oxygenation occurring in the placenta rather than in the lungs. Choice 4 is incorrect. The ductus venosus is a fetal structure connecting the umbilical vein to the inferior vena cava of the fetus, bypassing the fetal liver. It allows oxygenated blood from the placenta to bypass the liver and directly enter the fetal circulation. Choice 5 is incorrect. Thebesian veins or venae cordis minimae are tiny veins which return blood from the heart muscle itself into the right atrium. So the correct answer to question is choice 1.

Front 107

In the human embryo, during the third week of development, the first branchial arch divides to form the mandibular process and the
1. hyoid arch.
2. thyrohyoid arch.
3. branchial pouch.
4. maxillary process.
5. frontonasal process.

Back 107

MAXILLARY PROCESS

The correct answer is choice 4. Let's review the branchial arches and what structures are derived from them. The first branchial arch forms the mandibular process and the maxillary process through the formation of Meckel's cartilage. It also produces the malleus and incus. The second and third branchial arches form the components of the hyoid bone, while the second forms the styloid process and stapes. The fourth and sixth arches form the laryngeal cartilages. So choice 1, the hyoid, is from branchial arch 2 and 3. Choice 2, the thyrohyoid arch, is also from the second and third arches. Choice 3, branchial pouches or pharyngeal pouches, exist between the branchial arches and are not products of the branchial arches. Branchial pouches or pharyngeal pouches have their own derivatives. Choice 5 is incorrect. The frontonasal process is not formed from branchial arches. So the correct answer to question is choice 4.

Front 108

In the life cycle of an ameloblast, there are cells that contain Tomes' processes. These cells are in which of the following stages?
A. Secretory
B. Morphogenic
C. Organizing
D. Maturative
E. Protective

Back 108

SECRETORY

The correct answer is choice A. Tome's processes are extensions of ameloblast cytoplasm into the enamel matrix. They form at the apical end of the ameloblast, and contain secretory granules with the glycoprotein matrix of the enamel. Therefore, Tome's processes are involved in enamel matrix secretion. The opposite end of the ameloblast in the secretory phase contains the nucleus and numerous mitochondria. The correct answer to question is choice A.

Front 109

In the sulcular epithelium, small spaces between cells in the stratum spinosum (prickle cell layer) are normally filled by
1. keratin.
2. a small amount of tissue fluid.
3. capillaries that course between cells to approach the free surface.
4. none of the above.

Back 109

A SMALL AMOUNT OF TISSUE FLUID

The correct answer here is choice 2. The stratum spinosum is a cell layer within the sulcular epithelium. From the lowest underlying layer going towards the surface, the layers arc the stratum basale, the stratum spinosum, the stratum pranulosum and the stratum corneum. Reviewing the choices briefly: choice 1 is incorrect because keratin is found in the most superficial layer, the stratum corneum, but not in the stratum spinosum. It also should be noted that the keratin in the stratum corneum is contained within the cells and not between them. Choice 3 is incorrect because capillaries remain below the epithelial layer in the connective tissue layer. Choice 2 is correct. In general, all cells are surrounded by tissue fluid and this quality is not specifically applied only to sulcular epithelial stratum spinosum cells. Anyway, it is our correct answer to question.

Front 110

In the temporomandibular joint of an older person, the articulating surface of the temporal bone is covered by
1. hyaline cartilage.
2. elastic cartilage.
3. highly cellular fibrous connective tissue.
4. fibrous connective tissue containing chondrocytes.

Back 110

FIBROUS CONNECTIVE TISSUE CONTAINING CHONDROCYTES

The correct answer is choice 4. As a person becomes older, many degenerative changes occur in the body. The temporal mandibular joint is no exception. The degeneration in the temporal mandibular joint is marked by changes in the articulating surface of the temporal bone. It becomes covered by fibrous connective tissue containing chondrocytes, which produce small amounts of cartilage. This is choice 4. So the correct answer to question is choice 4.

Front 111

In which of the following are numerous afferent lymphatic channels found?
A. Spleen
B. Thymus
C. Lymph nodes
D. Palatine tonsils
E. Pharyngeal tonsils

Back 111

LYMPH NODES

The correct answer is choice C. All of the organs listed have some role in the lymphoid or immunologic system. The lymph node contains numerous afferent(inward) lymphatic channels. After lymph passes through these channels, it enters the sinuses of the node, where reticuloendothelial cells, including fixed macrophages, remove microorganisms and foreign material. The spleen contains similar reticuloendothelial cells, but they act to filter blood rather than lymph. The thymus gland produces lymphocytes and helps them specialize into "T-cell" types, but does not have incoming lymph channels. Both the palatine and pharyngeal tonsils can secrete antibodies (secretory IgA), but neither has incoming lymph channels. The correct answer to question is C.

Front 112

It is possible to distinguish histologically between the stomach and the duodenum because of the presence of
1. mucosal glands in the stomach only.
2. muscularis mucosa in the stomach only.
3. simple columnar epithelium lining the stomach only.
4. submucosal glands-in the duodenum only.
5. smooth muscle in the external musculature of the duodenum only.

Back 112

SUBMUCOSAL GLANDS

The correct answer is choice 4. Let's review the choices. Choice 1 is incorrect. The stomach contains mucosal cells which secrete pepsinogen, hydrochloride acid and intrinsic factor, as well as other materials. Likewise, in the duodenum, there are mucosal glands. However, the duodenum also contains mucous-secreting glands in the submucosa, while the stomach glands are all in the mucosal layer. Choice 2 is incorrect as both the stomach and duodenum conkin a muscularis mucosa layer. Choice 5 is incorrect as both organs are surrounded by smooth muscle. Choice 3 is incorrect. Both stomach and duodenum are lined by simple columnar epithelium. So the correct answer to question is choice 4.

Front 113

Lateral clefting of the lip results from the failure of merging of
1. maxillary with mandibular processes.
2. maxillary processes with each other.
3. maxillary and medial nasal processes.
4. medial and lateral nasal processes.
5. palatine processes with the nasal septum.

Back 113

MAXILLARY AND MEDIAL NASAL PROCESSES

The correct answer is choice 3. On each side of the face, the medial nasal process located at the midline of the face fuses with the maxillary process which is located further laterally. Failure to fuse can result in a cleft located slightly lateral to the midline on either the left or right side. Choice 1 is incorrect as the maxillary and mandibular processes do not normally merge. Choice 2 is incorrect. Failure of the two maxillary processes to merge is a rare event resulting in a midline cleft of the upper lip. Choice 4, failure of the medial and lateral nasal processes to join would lead to a deformation in the nasal area as the median nasal processes form the anterior nasal septum and the lateral nasal processes form the ala of the nose. Choice 5 is incorrect. Failure of the palatine process of the maxilla to merge with the nasal septum would cause a midline deformation rather than a lateral one. So the correct answer to question is choice 3.

Front 114

Long bones of the skeleton increase in length because of the
1. mitotic division of osteocytes.
2. mitotic division of osteoblasts.
3. resorption of primary bone by osteoclasts.
4. appositional growth on the cartilaginous epiphyseal plate.
5. interstitial growth in the cartilaginous epiphyseal plate.

Back 114

INTERSTITIAL GROWTH IN THE CARTILAGINOUS EPIPHYSEAL PLATE.

The correct answer is choice 5. Long bones such as those of the extremities have structurally distinct regions. The diaphysis makes up the shaft of the long bone. Its growth in thickness occurs by circumferential apposition of bone. The metaphyses make up the ends of the long bones. The epiphyses towards the ends of the long bones are separated from the metaphyses in a growing long bone by cartilaginous growth regions, called epiphyseal plates. Longitudinal growth occurs both proximally and distally from the epiphyseal plates by cartilage proliferation, cartilage calcification and eventually replacement by bone. So the correct answer to question is choice 5.

Front 115

Melanocytes are derived from which of the following?
A. Ectoderm
B. Endoderm
C. Mesoderm
D. Dermatomes
E. Neural crest

Back 115

NEURAL CREST

The correct answer is choice E. Melanocytes produce melanin, the dark colored skin pigment. They are derived from neural crest cells, which form from the neural fold area, which is originally ectoderm. Other derivatives of neural crest are craniospinal and a sympathetic ganglia, and the adrenal medulla. Mesoderm is involved in formation of the dermis while endoderm is not generally involved in skin formation. Dermatomes refer to areas of skin innervated by particular spinal nerves or groups of nerves. They are not germ layers, such as endoderm, mesoderm, etc. Note that choice A is a rational choice for this question, but choice C, neural crest, is closer to the formation of melanocytes than is ectoderm, which precedes neural crest. So our best answer to question is choice E.

Front 116

Most intrinsic muscles of the larynx receive their motor innervation from
1. the laryngeal plexus.
2. the inferior (recurrent) laryngeal nerve.
3. the external branch of the superior laryngeal nerve.
4. the internal branch of the superior laryngeal nerve.
5. both external and internal branches of the superior laryngeal nerve.

Back 116

INFERIOR (RECURRENT) LARYNGEAL NERVE

The correct answer is choice 2. Intrinsic laryngeal muscles include the cricothyroid, the cricoarytenoids, the arytenoids and the thyroarytenoid. These intrinsic laryngeal muscles alter the length and shape of the vocal cords and are involved in speech production. Most receive innervation from the recurrent laryngeal branch of the vagus nerve, choice 2. The cricothyroid is an exception which is innervated by the external laryngeal branch of the superior laryngeal nerve. So choices 3 and 5 are incorrect. Choice 4 is incorrect. The internal branch of the superior laryngeal nerve is primarily sensory and not motor. Choice 1 is incorrect. The laryngeal plexus is probably meant to refer to the pharyngeal plexus which innervates the three pharyngeal constrictor muscles. The correct answer to question is choice 2.

Front 117

Most of the antibodies in the body that act against bacterial antigens are produced by
1. T-lymphocytes.
2. B-lymphocytes.
3. macrophages.
4. plasma cells.

Back 117

PLASMA CELLS

The correct answer is choice 4. Antibodies are produced by plasma cells. These plasma cells are highly differentiated former B cells. The B cells become plasma cells under the influence of antigen, antigen antibody complexes, and sometimes helper T cells. Choice 1 is incorrect. T cells do not differentiate into plasma cells or produce antibodies. T cells recognize specific antigens and are involved in cell-mediated immunity, especially against fungi and viruses. They are also involved in cytotoxicity, graft rejection, immunologic memory, and they may help B cells to differentiate into plasma cells. Choice 2 is incorrect. B cells, as mentioned, may become plasma cells, but do not themselves produce antibodies. Choice 3 is incorrect. Macrophages engulf or phagocytize bacteria and also antibody-coated bacteria, sometimes following stimulation by T cells. So the correct answer to question is choice 4.

Front 118

Most of the fibers ascending to or descending from the cerebral cortex traverse the
1. pyramids
2. internal capsule.
3. medial lemniscus.
4. cerebral peduncles.

Back 118

INTERNAL CAPSULES

The correct answer is choice 2. The cerebral cortex is the thin outer sheet of grey matter covering the cerebral hemispheres. The vast majority of the afferent and efferent projection fibers of the cerebral cortex traverse the internal capsule, choice 2. The pyramids, choice 1, are prominent longitudinal ridges that run the length of the medulla oblongata. They contain corticospinal fibers. The medial lemniscus, choice 3, is formed by fibers originating in the dorsal column nuclei which transversely cross the medulla and then turn cranially close to the midline. The cerebral peduncles, choice 4, consist of a right and a left and they make up the midbrain. So the correct answer to question is choice 2.

Front 119

Most of the lymph is returned to the blood at which of the following sites?
1. Right brachiocephalic vein
2. Left external jugular vein
3. Junction of left internal jugular and subclavian veins
4. Junction of right internal jugular and subclavian veins

Back 119

JUNCTION OF LEFT INTERNAL JUGULAR AND SUBCLAVIAN VEINS

The correct answer is choice 3. Lymph is returned to the blood through a system of lymph channels or lymph veins. These are valved structures which return fluid to the blood system. When the lymph veins collect into larger lymph vessels, the largest lymph vessel, the thoracic duct, empties into the venous system at the junction of the left subclavian and left internal jugular veins. The thoracic duct begins below the level of the diaphragm, passes through the aortic opening of the diaphragm, and begins its ascent along the right side of the vertebral column, but changes to the left before it joins the veins at the junction of the left subclavian and left internal jugular veins. So the correct answer to question is choice 3.

Front 120

Movement of the head about its vertical axis (rotation to right or left) occurs chiefly at which of the following joints?
1. Atlanto-axial
2. Spheno-occipital
3. Atlanto-occipital
4. Third to seventh cervical vertebrae

Back 120

ATLANTO-AXIAL

The correct answer is choice 1. Rotation of the head occurs around the atlantoaxial joint. This refers to the joint between atlas and axis. The atlas is the first cervical vertebra while the axis is the second. In brief, the atlas can rotate on the axis which contains a peg-like projection or dens. Choice 2 is incorrect. The union between the sphenoid bone and occipital bone is osseous and no movement exists between these two bones. Choice 3, the atlantooccipital joint, refers to the union between the atlas and the occipital bone at the base of the skull. No rotational movement can occur here; only a nodding or bending movement. Some rotational movement exists in the third to seventh cervical vertebrae, but it is much less than that exhibited by the atlantoaxial joint. So the correct answer to question 50 is choice 1.

Front 121

Movement of which of the following joints causes lateral rotation of the head?
A. Atlanto-axial joint
B. Atlanto-occipital joint
C. Costochondral joint
D. Manubriosternal joint
E. Temporomandibular joint

Back 121

ATLANTO-AXIAL

the correct answer is A. Movement at the atlanto-axial joint (choice A) causes lateral rotation of the head. In other words, it involves moving the head in a manner as to say "no." Movement of the atlanto-occipital (choice B) joint causes flexion and extension, or nodding of the head to say "yes." Both the costochondral joint (choice C) and manubriosternal joint (choice D) are sternocostal articulations and are not associated with head movements. The temporomandibular joint (choice E) is between the mandibular fossa of the temporal bone and the condylar process of the mandible. This joint is associated with movement of the mandible.

Front 122

Normally, the free gingiva can be distinguished from the epithelial attachment because the
1. underlying connective tissue of the gingiva does not contain lymphoid cells.
2. epithelium of the epithelial attachment does not have rete pegs.
3. epithelium of the gingiva is not keratinized.
4. underlying connective tissue of the epithelial attachment is less vascular.

Back 122

EPITHELIUM OF THE EPITHELIAL ATTACHMENT DOES NOT HAvE RETE PEGS

Normally, the free gingiva can be distinguished from the epithelial attachment because the
1. underlying connective tissue of the gingiva does not contain lymphoid cells.
2. epithelium of the epithelial attachment does not have rete pegs.
3. epithelium of the gingiva is not keratinized.
4. underlying connective tissue of the epithelial attachment is less vascular.

Front 123

Odontoblasts are characterized by
A. being located on external surfaces of roots.
B. being shed from the tooth at the time of eruption
C. differentiating first at the cervical region of a forming tooth.
D. secreting a non-fibrous matrix composed of chains of amino acids.
E. possessing long cytoplasmic processes which lie within dentinal tubules.

Back 123

POSSESSING LONG CYTOPLASMIC PROCESSES WHICH LIE WITHIN DENTINAL TUBULES

The correct answer is choice E. In this question, there is a problem with each of the four first choices. In roots, cementoblasts are located externally and secrete cementum. Odontoblasts are located internally and secrete dentin. Odontoblasts, being located next to the pulp, are never shed. Ameloblasts are shed after eruption, with the loss of the enamel organ. Odontoblasts specialize at the coronal end of the tooth first. The tip of the crown is formed first, enamel by ameloblasts and dentin by odontoblasts. Development then proceeds in a cervical direction. The matrix secreted by odontoblasts is a chain of amino acids(protein), but is definitely fibrous (mostly collagen). Choice E is correct. Odontoblastic processes are long cytoplasmic extensions which lie in the dentinal tubules.

Front 124

Optic nerve fibers from the nasal half of the retina cross the midline and enter the optic tract of the opposite side by way of the
A. optic chiasma.
B. lateral geniculate body.
C. bipolar cells of the retina.
D. brachium of the superior colliculus.
E. geniculocalcarine tract (optic radiations).

Back 124

OPTIC CHIASMA

The correct answer is choice A. Optic nerve fibers undergo a partial decussation in the optic chiasm, with fibers from the nasal halves of each retina crossing while those from the temporal halves of each retina do not cross. Choice B is incorrect. The optic tracts which pass posteriorly from the optic chiasm terminate in the lateral geniculate bodies. These bodies give rise to neurons of the geniculocalcarine tracts (optic radiations), which pass posteriorly to the occipital cortex. Choice C is incorrect. Bipolar cells of the retina are the first neurons in the visual pathway. Choice D is incorrect. The brachium of the superior colliculus is a band of fibers which bypasses the lateral geniculate body to terminate directly in the superior colliculus. Choice E is incorrect.

Front 125

Pain fibers from the posterior third of the tongue travel with which cranial nerve?
A. Vagus
B. Facial
C. Trigeminal
D. Glossopharyngeal
E. Hypoglossal

Back 125

GLOSSOPHARYNGEAL

The correct answer is choice D. The glossopharyngeal nerve contains both general sensory and taste fibers from the posterior one-third of the tongue. Choice A is incorrect. The vagus contains some taste fibers from the most posterior portion of the tongue. Choice B is incorrect. The chorda tympani branch of the facial nerve conveys taste from the anterior two-thirds of the tongue.Choice C is incorrect. The lingual branch of V3 carries fibers which convey general sensation, including pain, from the anterior two-thirds of the tongue. Choice E is incorrect. The hypoglossal nerve is a motor nerve which supplies all intrinsic muscles of the tongue and all extrinsic muscles except palatoglossus.

Front 126

Pain, touch, temperature and proprioceptive modalities for the temporomandibular joint are carried by way of which of the following nerves?
A. Auriculotemporal
B. Auditory
C. Temporal
D. Superior alveolar
E. Inferior alveolar

Back 126

AURICULOTEMPORAL

The correct answer is choice A. The auriculotemporal nerve is a sensory branch of V3 which travels within the parotid gland conveying sensory information from the face and temporomandibular joint. Choice B is incorrect. The auditory, or vestibulocochlear, nerve conveys the special senses of hearing and equilibrium from the inner ear. Choice C is incorrect. Temporal nerves are of two kinds: motor branches of CN VII, to muscles of facial expression, and deep temporal branches of V3, which supply the temporalis muscle with motor fibers. Choice D is incorrect. Superior alveolar nerves are branches of the maxillary division of the trigeminal which supply the maxillary sinus, gingiva and teeth. Choice E is incorrect. The inferior alveolar nerve is a branch of V3 which conveys sensory information from the mandibular teeth and gingiva. It also has a motor branch to mylohyoid and anterior belly of digastric.

Front 127

Parasympathetic innervation controlling salivation originates with which of the following cranial nerves?
A. V,VII, IX,X,and XII
B. V,VII, IX, and X
C. V, IX, and X
D. VII, IX,and XI
E. VII and IX

Back 127

VII AND IX

The correct answer is choice E.
CN VII contains preganglionic parasympathetic fibers which travel in the chorda tympani to synapse in the submandibular ganglion. Postganglionic fibers then pass to the sublingual and submandibular salivary glands. CN IX contains fibers which travel in the tympanic nerve and lesser petrosal nerve to synapse in the otic ganglion. Postganglionic parasympathetic fibers then travel in the auriculotemporal branch of V3 to reach the parotid gland. Choice A is incorrect. CN's V and XII do not contain preganglionic parasympathetic fibers. CN X has a parasympathetic component which distributes to viscera of thorax and abdomen. Choice B is incorrect. CN V is not a parasympathetic nerve. CN X does not innervate salivary glands. Choice C is incorrect. CN V is not a parasympathetic nerve, although it does transport postganglionic parasympathetic fibers to their destinations. Choice D is incorrect. CN XI does not contain preganglionic parasympathetic fibers.

Front 128

Peripheral (lower motor neuron) lesions of cranial nerve VII will cause which of the following?
A. A contralateral paralysis of the facial musculature
B. An ipsilateral flaccid paralysis of the facial musculature
C. A contralateral paralysis of only the lower facial muscles
D. A contralateral paralysis of only the upper facial muscles
E. An ipsilateral flaccid paralysis of only the lower facial muscles

Back 128

AN IPSILATERAL FLACCID PARALYSIS OF THE FACIAL MUSCULATURE

The correct answer is choice B.
Damage to the motor root of CN VII will cause paralysis of the facial muscles on the same (ipsilateral) side as the lesion. If the nerve is damaged before it ramifies within the parotid gland, all the muscles of facial expression will be affected. Choice A is incorrect. Contralateral refers to muscles on the side of the face opposite the lesion. Choice C is incorrect. If the marginal mandibular branch of CN VII were selectively damaged, an ipsilateral paralysis of the lower facial muscles would result.Choice D is incorrect. Contralateral paralysis of only the lower facial muscles would result from a central (upper motor neuron) lesion. Choice E is incorrect.

Front 129

Pharyngotympanic (eustachian) tubes connect the nasopharynx with the
1. outer ear.
2. middle ear.
3. semicircular canals.
4. vestibule of the inner ear.

Back 129

MIDDLE EAR

The correct answer is choice 2. The pharyngotympanic tube or eustachian tube connects the nasopharynx and the middle ear. It extends downward, forward and inward towards the nasopharynx. Its function is to equalize pressure against the inner and outer surfaces of the tympanic membrane. Pathologically, it is also a root by which infections may travel from the throat into the ear. The eustachian tube does not connect to the outer ear (choice 1) or the inner ear which contains the semicircular canals (choice 3) and vestibule (choice 4). It should be noted that the middle ear is the area containing the malleus, incus and stapes, known as the ear bones, hammer, anvil and stirrup. So the correct answer to question is choice 2.

Front 130

Preganglionic parasympathetic fibers pass through which of the following structures?
1. Foramen ovale
2. Stylomastoid foramen
3. Foramen magnum and hypoglossal canal
4. Superior orbital fissure and petrotympanic fissure

Back 130

SUPERIOR ORBITAL FISSURE AND PETROTYMPANIC FISSURE

The correct answer is choice 4. The cranial preganglionic neurons are found in the parasympathetic efferent nuclei of the brainstem. Their axons pass in third (or oculomotor), 7th (or facial), 9th (glossopharyngeal), and tenth (vagus) cranial nerves. The oculomotor nerve exits the cranium via the superior orbital fissure. The facial nerve passes through the skull via the stylomastoid foramen and its branch, the chorda tympani, exits via the petrotympanic fissure. The glossopharyngeal and the vagus nerves leave the cranium through the jugular foramen. Therefore, the correct answer is choice 4, superior orbital fissure and petrotympanic fissure. Choice 1, the foramen ovale, transmits the mandibular branch of the trigeminal nerve, cranial nerve V. Choice 2, the stylomastoid foramen, transmits the facial nerve, cranial nerve VII. This choice is also correct but since the question asks for all structures which preganglionic parasympathetic fibers pass through, choice 4 is the more appropriate answer. Choice 3, the foramen magnum, passes the spinal accessory, cranial nerve XI, and the hypoglossal canal transmits the hypoglossal nerve, cranial nerve XII. So the correct answer to question is choice 4.

Front 131

Primary afferent neurons in the gag reflex are carried by which of the following cranial nerves?
A. Vagus (X)
B. Facial (VII)
C. Trigeminal (V)
D. Hypoglossal (XII)
E. Glossopharyngeal (IX)

Back 131

GLOSSOPHARYNGEAL

The correct answer is choice E. The mucosa of the back of the throat (oropharynx) is supplied with sensory innervation by fibers from CN IX as part of the pharyngeal plexus, which is composed of fibers from CN's IX, X, and XI. Choice A is incorrect. The vagus does not convey sensory information from the oropharynx. Choice B is incorrect. The facial nerve may cany fibers conveying taste from the soft palate via the greater superficial petrosal nerve. Choice C is incorrect. Sensory fibers from the nasopharynx form the pharyngeal branch of V2, the maxillary nerve. Choice D is incorrect. The hypoglossal nerve is a motor nerve supplying the muscles of the tongue.

Front 132

Production of bile takes place in
1. Kupffer cells.
2. the gallbladder.
3. the hepatic duct.
4. the common bile duct.
5. none of these.

Back 132

NONE OF THESE

The correct answer is choice 5. Bile plays an important role in digestion. The function of bile is to aid in the emulsification of fats to solubilized monoglycerides in water prior to absorption and to retard putrefaction. Bile is secreted by the hepatocytes of the liver. It is concentrated and stored in the gallbladder and emptied into the duodenum in response to a meal. Kupffer cells, choice 1, are the phagocytic cells of the liver. They remove spent erythrocytes and other particulate debris from circulation. The gallbladder, choice 2, concentrates and stores bile but does not produce it. The hepatic duct, choice 3, and the common bile duct, choice 4, are external structures of the hepatic tree. They do not produce bile. So the correct answer to question is choice 5.

Front 133

Right subclavian and right common carotid arteries arise from the
1. thoracic aorta.
2. ascending aorta.
3. arch of the aorta.
4. pulmonary artery.
5. brachiocephalic artery.

Back 133

BRACHIOCEPHALIC ARTERY

The correct answer is choice 5. The brachiocephalic artery arises from the arch of the aorta and divides into the right subclavian and right common carotid arteries. By contrast, the left common carotid arises directly from the arch of the aorta -- that is incorrect choice 3 -- as does the left subclavian. So choice 3 is correct for the left side, but not for the right side. Choice 1 is incorrect. The thoracic aorta refers to the section of the aorta following the aortic arch. It gives rise to a number of branches including the bronchial arteries and the intercostal arteries. Choice 2, the ascending aorta, refers to the section of aorta beginning at the left ventricle and continuing to become the aortic arch. It gives off branches only of the right and left coronary arteries. Choice 4 is incorrect. The pulmonary artery carries deoxygenated blood to the lungs and does not give off any systemic branches. So the correct answer to question is choice 5.

Front 134

Salivary gland striated ducts are composed of which of the following types of epithelium?
A. Simple squamous
B. Simple cuboidal
C. Stratified squamous
D. Simple low columnular
E. Psuedostratified ciliated columnar

Back 134

SIMPLE LOW COLUMNAR

The correct answer is choice D. Striated cells of salivary gland ducts are simple(one layer) columnar cells. At their base, there is a large concentration of mitochondria which give the cell a striped appearance. The organelles provide energy for transport of water and salt ions, and are present in great numbers whenever energy need is high. Note that most acinar cells (which produce secretions)of salivary glands are simple cuboidal. The correct answer to question is choice D.

Front 135

Salivary glands of the hard palate are located in the
1. median raphe.
2. gingival zone.
3. anterolateral zone.
4. posterolateral zone.

Back 135

POSTEROLATERAL ZONE

The correct answer is choice 4. Salivary glands, which secrete a fluid called saliva, aid in the mastication, digestion and deglutition of food. These glands are present in various numbers and sizes throughout the oral cavity. In the hard palate, salivary glands are found in the submucosal layer situated in the posterolateral zone, choice 4. These glands seldom extend anteriorly beyond the line drawn from one first molar to the other. Posteriorly, they increase in size and thickness and reach far into the soft palate. So the correct answer to question is choice 4.

Front 136

Salivary, sweat, sebaceous, and von Ebner's glands all have in common the characteristic of being
1. simple.
2. compound.
3. exocrine.
4. holocrine.
5. merocrine.

Back 136

EXOCRINE

The correct answer is choice 3. Glands are divided into two main categories based on their structure and function. The exocrine glands contain ducts in which their secretions leave the gland. The endocrine glands do not contain ducts but pour their secretions directly into the circulation. The exocrine glands are further subdivided into holocrine, choice 4, in which the cells composing the gland break down completely in order to liberate their secretion, apocrine, in which some of the cytoplasm at the free surface of the cells composing the gland is discharged with the secretion and merocrine, choice 5, which discharge their secretion without any fragmentation of the cytoplasm of their cells. Exocrine glands may also be described as simple, choice 1, those glands with a single unbranched duct or compound, choice 2, those glands with a branched duct system. Salivary glands are exocrine in nature and belong to a the subdivision of being compound and merocrine in secretion. Sweat glands are exocrine in nature and are simple and apocrine in secretion. Sebaceous glands are exocrine, simple and holocrine in secretion. Von Ebner's glands are also glands with ducts and are compound with merocrine secretion. These glands are all exocrine, choice 3, in nature but are all different in their subdivisions. So the correct answer to question is choice 3.

Front 137

Second, third and fourth right posterior intercostal veins drain from the right superior intercostal vein into the
1. azygos vein.
2. hemiazygos win.
3. accessory hemiazygos vein.
4. left brachiocephalic vein.
5. left internal jugular vein.

Back 137

AZYGOS VEIN

The correct answer is choice 1. Intercostal veins from left, right, and upper and lower ribs end up draining into different larger veins. The highest posterior intercostal vein drains into either the brachiocephalic or vertebral vein. The second, third and fourth right posterior intercostal veins drain into the superior intercostal vein which joins the azygos vein, choice 1, our correct answer. The left superior intercostal vein drains into the left brachiocephalic vein. The remaining right intercostal veins drain into the azygos and the remaining left intercostal veins drain into the hemiazygos and accessory hemiazygos veins. So we see that choices 2, 3 and 4 are incorrect but are involved in intercostal drainage. Choice 5, the internal jugular vein, is not involved in intercostal drainage. So our correct answer to question is choice 1.

Front 138

Skeletal muscle enlarges with prolonged activity as a consequence of
1. differentiation of myoblasts.
2. mitotic division of muscle fibers.
3. an increase in endomysial connective tissue.
4. an increase in sarcoplasm and in the number of myofibrils of existing muscle fibers.

Back 138

AN INCREASE IN SARCOPLASM AND IN THE NUMBER OF MYOFIBRILS OF EXISTING MUSCLE FIBERS

The correct answer is choice 4. As you know from experience, muscle size can increase through exercise over long periods of time. This is due to an increase in amount of sarcoplasm and an increased number of myofibrils. The sarcoplasm refers to the cytoplasm of the fiber which is the multinucleated muscle cell. Within each fiber are myofibrils which are the contractile elements of the fiber. So both the amount of sarcoplasm and the number of myofibrils can increase through exercise. Choice 1 is incorrect. Myoblasts are precursor cells of fibers and do not differentiate because of exercise; rather, they differentiate during embryonic muscle formation. Choice 2 is incorrect. Muscle fibers, or cells, once formed, generally do not undergo further mitosis. Choice 3 is incorrect. Endomysium is a thin connective tissue separating the individual fibers and it does not grow due to exercise. So the correct answer to question is choice 4.

Front 139

Some medications can be absorbed through the mucosa of the tongue's ventral surface and through the mucosa of the floor of the mouth. This absorption can take place in these areas because the mucosa is
A. covered by pseudostratified squamous epithelium.
B. covered by simple squamous epithelium with a vascular lamina propria.
C. covered by thin nonkeratinized stratified squamous epithelium with a thin lamina propria.
D. covered by keratinized stratified squamous epithelium that contains numerous capillaries.
E. pierced by the ducts of numerous minor salivary glands through which some types of medication are easily absorbed.

Back 139

COVERED BY THIN NONKERATINIZED STRATIFIED SQUAMOUS EPITHELIUM WITH A THIN LAMINA PROPRIA

The correct answer is choice C. Some medications are taken by dissolving them under the tongue and absorbing them by diffusion. The ease of diffusion is due to the fact that the epidermis is thin in this area and is composed of stratified(1ayered) squamous(flat) cells. This epithelium is non-keratinized. Medications will diffuse most readily through non-keratinized tissue. Lamina propria refers to loose connective tissue underneath the epithelial layer. On the ventral tongue, this is also thin. The correct answer to question is choice C.

Front 140

The long axes of mandibular condyles intersect at the foramen magnum indicating that these axes are directed
1. transversely.
2. anteroposteriorly.
3. anteromedially.
4. posteromedially.
5. None of the above

Back 140

The correct answer is choice 4, posteromedially..... The foramen magnum is the large foramen at the base of the skull through which the spinal fl cord will pass. Review a model diagram or preserved specimen of a mandible and a skull for this question. The condyle of the mandible terminates in pointed areas known as the medial and lateral poles. Lines drawn through the poles from each side will extend horizontally medially and posteriorly until they meet near the anterior border of the foramen magnum. This is, therefore. a medial and posterior direction, choice 4. It is said that this line is parallel to a line connecting the buccal and lingual cusps of the premolar and molar teeth although the significance of this parallelism is not known. Anyway, the correct answer to question is choice 4.

Front 141

The lymph from the upper lateral quadrant of the mammary gland primarily drains into the
A. Anterior (pectoral) axillary nodes
B. Central axillary nodes
C. Infraclavicular (deltopectoral) axillary nodes
D. Lateral axillary nodes

Back 141

The correct answer is A, the anterior (pectoral) axillary nodes..... The axillary lymph nodes drain lymph vessels from the lateral quadrants of the breast, superficial lymph vessels of the thoracoabdominal walls above the umbilicus and the vessels from the upper limb. The lymph from the upper lateral quadrant of the mammary gland primarily drains into the anterior (pectoral) axillary nodes (choice A). The central axillary nodes (choice B) receive lymph from the anterior, posterior and lateral axillary lymph nodes. The infraclavicular (deltopectoral) axillary nodes (choice C) receive lymph from the lateral'side of the hand, forearm and arm. The lateral axillary nodes (choice D) receive most of the lymph from the upper arm and the posterior (subscapular) axillary nodes (choice E) receive lymph vessels from the back extending down as far as the iliac crest.

Front 142

The lymph vessels that drain both dental arches connect directly with which of the following nodes?
A. Submandibular
B. Deep cervical
C. Sublingual
D. Retropharyngeal
E. Superficial cervical

Back 142

The correct answer is choice A, the submandibular nodes.... Gingival and dental lymphatic vessels drain to the submandibular nodes of their respective sides. An exception is the region of the lower four incisor teeth, which drain to submental lymph nodes. Choice B is incorrect. All head and neck lymphatics drain ultimately to deep cervical nodes, either directly or indirectly. Submandibular nodes drain to deep cervical nodes. Choice C is incorrect. Sublingual nodes are small and variable. They drain to deep cervical nodes. Choice D is incorrect. Retropharyngeal nodes receive afferents from the nasopharynx and Eustachian tube. They drain to deep cervical nodes. Choice E is incorrect. Superficial cervical nodes receive lymph from the external ear and lower parotid region. They drain to deep cervical nodes.

Front 143

The mandible, except for the condyle, is principally formed by
1. endochondral ossification.
2. intramembranous ossification.
3. expansion of the dental lamina.
4. the conversion of Meckel's cartilage directly into bone.

Back 143

The correct answer is choice 2, intramembranous ossification..... The mandible ossifies in membrane (intramembranous ossification) from two centers that appear close to the site of the future mental foramen during the sixth week of intrauterine life. The Meckel's cartilage provides a framework around which the mandible forms. Between the 10th and 14th week, three secondary cartilages develop within the growing mandible. The largest and most important of these is the condylar cartilage. In short, the mandible is principally formed by intramembranous ossification while the condyle is formed by secondary cartilage. So the correct answer to question is choice 2.

Front 144

The middle constrictor muscle of the pharynx originates from the
1. hyoid bone.
2. thyroid cartilage.
3. pterygoid hamulus.
4. pterygomandibular raphe.

Back 144

The correct answer is choice 1, the hyoid bone.... The middle constrictor muscle connects the lower section of the stylohyoid ligament to the greater and lesser horns of the hyoid bone. It is involved in involuntary contraction during swallowing. Choice 2 is incorrect. The thyroid cartilage has muscle attachments for the cricothyroid muscle. Choice 3 is incorrect. The pterygoid hamulus is a process around which the tensor veli palatini muscle hooks. The tensor veli palatini tightens and flattens the soft palate. Choice 4 is incorrect. Pterygomandibular raphe is a frbrous line of connective tissue which attaches to the superior constrictor and buccinator muscles. So the correct answer to question is choice 1.

Front 145

The middle nasal concha is part of which of the following bones?
1. Nasal
2. Vomer
3. Ethmoid
4. Palatine
5. Sphenoid

Back 145

The correct answer is choice 3, the ethmoid bone....The ethmoid bone consists primarily of the two lateral masses, one on each side of the nasal cavity. It is notable for containing the cribriform plate through which the olfactory and anterior ethmoidal nerves pass. It also contains many hollow air cells and both the superior and middle conchae of the nose. Choice 1, the nasal bones, a seemingly logical choice, do not contain any conchae of the nose. The two nasal bones are small and border on the nasal cartilage, the nasal spine of the m frontal bone, the perpendicular plate of the ethmoid, and the maxilla. The vomer, choice 2, forms the posterior part of the nasal septum and does not contain a nasal concha. Choice 4, the palatine bone, borders on the inferior nasal concha which is a separate bone, as does the maxilla. Choice 5, the sphenoid, also does not contain the nasal conchae. So the correct answer to question is choice 3.

Front 146

The middle pharyngeal constrictor muscle originates from the
1. hyoid bone.
2. thyroid cartilage.
3. pterygoid hamulus.
4. pterygomandibular raphe.

Back 146

The correct answer is choice 1, the hyoid bone.... The middle pharyngeal constrictor muscle arises from the whole length of the superior border of the greater horn of the hyoid bone, from the lesser horn, and from the inferior end of the stylohyoid ligament. The fibers course posteriorly to be inserted into the median raphe. So the correct answer to question is choice 1.

Front 147

The most common immunoglobulin found in mucosal secretions of the respiratory and gastrointestinal tract and colostrum is
A. IgA
B. IgD
C. IgE
D. IgG
E. IgM

Back 147

The correct answer is A, IgA.... Immunoglobulin A (IgA) (choice A) helps to defend against bacteria on mucosal surfaces. When IgA is deficient, there is an increased susceptibility to infections, especially upper-respiratory infections. IgD (choice B) plays a minor role in the bodies immune system. IgE (choice C) is primarily involved in allergic reactions. Both IgG (choice D) and IgM (choice E) are involved in the majority of all bacterial infections. These antibodies, as well as IgA, IgD and IgE, protect the body by directly attacking the "invader" as well as activating the complement system.

Front 148

The most prominent functional component in the tunica media of small arteries is
1. elastic fibers.
2. smooth muscle.
3. striated muscle.
4. reticular fibers.
5. collagenous fibers

Back 148

The correct answer is choice 2, smooth muscle.....Arteries consist of a tunica intima or inner layer, a tunica media or middle layer, and a tunica adventitia or outer layer. The tunica intima generally contains epithelium and elastic fibers. The tunica media is generally composed of smooth muscle with some few reticular fibers, elastic fibers and collagen fibers. However, the major distinguishing component is smooth muscle. The tunica adventitia is characterized by collagen fibers. So, reviewing our choices: choice 1, elastic fibers are present in the tunica media but are not the most prominent; choice 3, striated muscle is not present in the artery; choice 4, reticular fibers are present in the tunica media but are, again, not the most prominent; choice 5, collagen fibers are characteristic of the tunica adventitia, not the tunica media. So the correct answer to question is choice 2.

Front 149

The most vascular portion of the temporomandibular joint's articular disk is usually found on the disk's
1. periphery.
2. superior surface.
3. inferior surface.

Back 149

The correct answer is choice 1, the periphery.... The temporal mandibular joint is the synovial articulation between the mandible and the cranium. A fibrocartilage biconcave articulating disks interposed between the rounded condyle of the mandible and the corresponding articular surface of the temporal bone. The articulatlng disk is supplied by an impressive compact crown of interwined capillary twigs hugging the thick rim of the avascular fibrous disk. The most vascular portion of the disk, therefore, is found on the periphery. So the correct answer to question 16 is choice 1.

Front 150

The muscle that is the prime mover in left lateral excursion is the
A. right masseter.
B. left medial pterygoid.
C. right medial pterygoid.
D. left lateral pterygoid.
E. right lateral pterygoid

Back 150

The correct answer is choice E, right lateral pterygoid..... Acting together, the lateral pterygoids protrude the mandible and open the jaw. Acting individually, they cause movement of the mandible to the opposite side (right lateral pterygoid moves the mandible to the left). Choice A is incorrect. The major function of the masseter is to elevate the mandible (close the jaw). Choice B is incorrect. Acting together, the medial pterygoids elevate the mandible. Choice C is incorrect. Choice D is incorrect.

Front 151

The nerves in dental pulp are
1. afferent only.
2. sympathetic only.
3. parasympathetic only.
4. afferent and sympathetic.
5. afferent and parasympathetic.

Back 151

The correct answer is choice 4, afferent and sympathetic.... Compared to a similar volume of connective tissue elsewhere in the body, the dental pulp is richly innervated. The pulp is supplied with thick bundles of myelinated fibers with fine nonmyelinated terminals extending into the predentin, some of which may run through the dentinal tubules to he dentin. These fibers are both afferent or sensory and sympathetic, choice 4. It's important to note that there are no motor nerves to the dental pulp and no parasympathetic nerves to the dental pulp. So the correct answer to question is choice 4.

Front 152

The nucleolus produces
1. DNA.
2. transfer RNA.
3. ribosomal RNA.
4. messenger RNA.
5. both (1) and (2) above

Back 152

The correct answer is choice 3, ribosomal RNA..... The nucleolus of the cell located within the nucleus is composed of and produces rRNA or ribosomal RNA. rRNA comprises the bulk of the structure of the ribosome. Choice 1 is incorrect. DNA is produced by replication in the nucleus, but outside of the nucleolus. Choice 2 is incorrect. Transfer RNA is also synthesized in the nucleus, but not in the nucleolar region. Choice 4 is incorrect. Messenger RNA is produced by transcription from the DNA in the nucleus, but outside of the nucleolus. So the correct answer to question is choice 3.

Front 153

The number of roots that are formed is determined by the
1. thickness of the cervical loop.
2. number of root sheaths developed by the enamel organ.
3. number of discontinuities developed in the root sheath.
4. number of medial ingrowths of the cervical loop.

Back 153

The correct answer is choice 4, the number of medial ingrowths of the cervical loop..... After full formation of enamel, the inner and outer enamel epithelium meet to form the cervical loop, the tip of which becomes Hertwig's root sheath. The Hertwig root sheath will cause root formation through induction of the cells of the dental papilla to become odontoblasts. As the cervical loop forms inpockets or ingrowths, various numbers of roots will form. Choice 1 is therefore incorrect. Likewise, choice 2 is incorrect. The enamel organ itself does not form the root sheath. It is only the inner and outer enamel epithelium at their tip which form the root sheath and only after enamel formation is complete. Choice 3 is incorrect. Hertwig's root sheath is perforated by dental sac tissue which will become the periodontal ligament. However, these perforations are not involved in determining the number of roots. So the correct answer to question is choice 4.

Front 154

The obliquus superior muscle is innervated by which of the following nerves?
A. Abducent
B. Accessory
C. Oculomotor
D. Optic
E. Trochlear

Back 154

The correct answer is E, the trochlear nerve..... The trochlear nerve (choice E) is involved with ocular movement and innervates the obliquus superior muscle. The abducent nerve (choice A) is also involved with ocular movements. It innervates the rectus lateralis muscle. The accessory nerve (choice B) innervates various muscles in the pharynx, larynx, and shoulders, including sternocleidomastoid and trapezius. It is involved with swallowing, phonation, and movements of the head and shoulder. The oculomotor nerve (choice C) is responsible for ocular movement, contraction of the pupil and accommodation. This nerve innervates various eye muscles, including the obliquus inferior. The optic nerve (choice D) is responsible for vision and innervates rods and cones of the retina.

Front 155

The optic tracts consist of axons from which of the following cells?
1. Rod
2. Bipolar
3. Ganglion
4. Horizontal
5. All of the above

Back 155

The correct answer is choice 3, ganglion cells..... Let's review the cells associated with vision. The sensory cells, rods, choice 1, and cones lie in the external layer of the retina and activate the bipolar cells (choice 2) of the middle layer. The innermost layer contains ganglion cells (choice 3), our correct answer. The fibers of the ganglion cells converge to form the optic nerve and optic tract to the visual cortex. Choice 4, horizontal cells, lie in the middle layer of the retina and interconnect rods, cones, ganglion cells and bipolar cells. The correct answer to question is choice 3.

Front 156

The organelle that binds and releases calcium during relaxation and contraction of skeletal muscle is a
1. nucleus.
2. lysosome.
3. mitochondrion.
4. transverse tubule.
5. sarcoplasmic reticulum

Back 156

The correct answer is choice 5, the sarcoplasmic reticulum..... The sarcoplasmic reticulum releases calcium ions when muscles contract and binds them during muscle relaxation. The sarcoplasmic reticulum tubules run parallel to the muscle fibers. Choice 1, nucleus, is incorrect. The nucleus stores genetic material in the form of DNA and directs the cell's activities. Choice 2 is incorrect. The lysosome stores digestive enzymes within a membrane. Choice 3 is incorrect. The mitochondrion produces ATP molecules through oxidative phosphorylation and the oxidative degeneration of glucose. Choice 4 is incorrect. The transverse tubules are separate from the sarcoplasmic reticulum. They extend transversely into the sarcoplasm and are invaginations of the sarcolemma membrane. They are not involved in calcium binding or calcium release. So the correct answer to question is choice 5.

Front 157

The organic matrix of dentin is synthesized by which of the following?
A. Ameloblasts
B. Cementocytes
C. Odontoblasts
D. Osteoblasts
E. Osteocytes

Back 157

The correct answer is C, odonotoblasts..... Teeth are composed of a core pulp surrounded by a mineralized dentin, which is covered by a mineralized enamel on the crown and a mineralized cementum on the root. Dentin contains an organic matrix composed of collagen and proteoglycans synthesized by odontoblasts (choice C). Ameloblasts (choice A) produce the hardest substance of the human body known as enamel. Cementocytes (choice B) produce a calcified tissue similar to that of bone that covers the dentin of the root. This substance is called cementum. Osteoblasts (choice D) are the basophilic cells that actively secrete bone matrix and osteocytes (choice E) are mature bone cells.

Front 158

The parotid duct pierces the buccinator muscle opposite the
1. mandibular first premolar.
2. maxillary first premolar.
3. maxillary first molar.
4. maxillary second molar.
5. maxillary third molar.

Back 158

The correct answer is choice 4, maxillary second molar.... The parotid gland is the largest of the paired salivary glands and contains serous rather than mucous acini, and is located in a space roughly bordered by the styloid process, the external auditory meatus and the mastoid process. The parotid duct or Stensen's duct leaves the anterior border of the gland and pierces the buccinator muscle to enter the oral cavity on the buccal surface opposite the second maxillary molars. Of the incorrect choices, it should be noted that the sublingual and submandibular glands empty into the floor of the mouth and might be considered to be opposite the mandibular teeth. The submandibular gland drains through Wharton's duct into the floor of the mouth, while the sublingual gland drains through a large number of openings in the floor of the mouth. So the correct answer to question is choice 4.

Front 159

The point on the lateral aspect of the skull where the greater wing of the sphenoid, parietal, frontal and temporal bones converge is known as the
A. Asterion
B. Bregma
C. Lambda
D. Pterion
E. Stephanion

Back 159

The correct answer is D, pterion...... The point on the lateral aspect of the skull where the greater wing of the sphenoid, parietal, frontal and temporal bones converge is known as the pterion (choice D). The asterion (choice A) is the point of meeting of the parietomastoid, occipitomastoid and lambdoidal sutures. The bregma (choice B) is the point at which the coronal suture intersects the sagittal suture and is the site of the anterior fontanelle in an infant. The lambda (choice C) is the point at which the sagittal suture intersects the lamboid suture and is the site of the posterior fontanelle in an infant. The stephanion (choice E) is the point where the superior temporal line cuts the coronal suture.

Front 160

The postcentral gyrus is located in the
1. insula.
2. frontal lobe.
3. temporal lobe.
4. parietal lobe.
5. occipital lobe.

Back 160

The correct answer is choice 4, the parietal lobe..... The postcentral gyrus is the primary sensory area of the brain receiving general sensation from the contralateral side of the body via relays in the thalamus. The postcentral gyrus is located in the parietal lobe, choice 4, of the brain. So the correct answer to question is choice 4.

Front 161

The posterior cervical triangle is bounded partly by
1. trapezius and subclavius muscles.
2. splenius capitis and trapezius muscles.
3. trapezius and sternocleidomastoid muscles.
4. the clavicle and the longus colli muscle.

Back 161

The correct answer is choice 3, trapezius and sternocleidomastoid muscles..... The side of the neck is often thought of as being divided into two triangles. The sternocleidomastoid muscle divides the area into an anterior and posterior triangle. The posterior triangle is bounded by the clavicle, the posterior border of the stenzocleidomastoid and the anterior border of the trapezius. The anterior triangle is bordered by the anterior side of the sternocleidomastoid, the lower border of the mandible, and the midline of the neck. Choice 1 is incorrect. The subclavius is a muscle located underneath the pectoralis major and inserts on the clavicle and first rib. Choice 2 is incorrect. The splenius capitis is a muscle which extends the head and neck and is located in the floor of the posterior triangle and inserts on the mastoid process. Choice 3 is incorrect. The longus colli is a muscle of the prevertebral group and inserts on the vertebrae. So the correct answer to question is choice 3.

Front 162

The posterior cord of the brachial plexus gives rise to which of the following nerves?
1. Radial
2. Long thoracic
3. Thoracoacromial
4. Medial pectoral
5. Lateral pectoral

Back 162

The correct answer is choice 1, the radial nerve...... The brachial plexus is a network of nerves which provides innervation primarily to the upper extremity. It is subdivided into roots, trunks, divisions and cords. Each of these are then further named according to the positions in the plexus. For example, the cords are referred to as lateral, medial and posterior cords. The radial nerve, choice I, is a branch of the posterior cord. The long thoracic nerve, choice 2, originates from the roots of the brachial plexus. The thoraco-acromial, choice 3, usually refers to a large artery and its branches that supply the upper extremity. The medial pectoral nerve, choice 4, branches off the medial cord and the lateral pectoral nerve, choice 5, branches off the lateral cord. So the correct answer to question is choice 1.

Front 163

The postganglionic sympathetic fibers to the vessels of the submandibular salivary gland arise from cells in the
1. otic ganglion.
2. submandibular ganglion.
3. pterygopalatine ganglion.
4. superior cervical ganglion.

Back 163

The correct answer is choice 4, the superior sympathetic ganglion...... The submandibular salivary gland folds around the posterior edge of the mylohyoid muscle so that one section is within the oral cavity and the other is outside. It is innervated by parasympathetic secretomotor fibers from cranial nerve 7, the facial nerve. These post-ganglionic fibers begin in the submandibular ganglion, choice 2. However, post-ganglionic sympathetic fibers also innervate the gland. These fibers come from synapses in the superior cervical ganglion which contains the synapse between the post-ganglionic fibers and the pre-ganglionic fibers which run up from the thoracic vertebrae into the inferior, middle and superior cervical ganglia. So our correct answer is choice 4. Choice 1 is incorrect. The otic ganglion contains cell bodies of post-ganglionic fibers which are secretomotor to the parotid gland. The post-ganglionic fibers travel via the auriculotemporal nerve. The pre-ganglionic neurons originate with cranial nerve 9, the glossopharyngeal. Choice 3 is incorrect. The pterygopalatine ganglion contains post-ganglionic fibers which are secretomotor to the lacrimal, nasal and palatine glands. So the correct answer to question is choice 4.

Front 164

The presence of valves characterizes
1. veins only.
2. blood sinusoids only.
3. lymphatic vessels only.
4. veins and lymphatic vessels.
5. blood sinusoids and blood capillaries.

Back 164

The correct answer is choice 4, veins and lymphatics..... Within the circulatory system, valves can be found in veins of more than 2mm in diameter and in small and medium sized lymphatic vessels, choice 4. Blood sinusoids, choice 2, are capillaries of wide diameter but do not contain valves. Blood capillaries, choice 5, are small blood vessels with diameters similar to that of a red blood cell and in general, these do not have valves. So the correct answer to question is choice 4.

Front 165

The primary histologic characteristic of the pancreas is
1. follicles filled with secretion.
2. groups of special cells scattered among glandular alveoli.
3. small groups of cells scattered between follicles.
4. cells arranged in layers among which are special cells.

Back 165

The correct answer is choice 2, groups of specialized cells scattered among glandular alveoli..... The pancreas is both an exocrine and endocrine gland. The exocrine cells produce digestive enzymes and their enzymatic secretions enter ducts which eventually enter the duodenum. Scattered within areas of exocrine cells are endocrine areas of cells called islets of Langerhans. These areas contain alpha cells which produce glucagon and beta cells which produce insulin. Their endocrine secretions pass directly into the blood stream without passing through ducts. Choices 1 and 3 are incorrect. The term "follicle" is usually used to describe hair follicles or ovarian follicles and applies a large area filled with a substance or secretion, such as an ovum or a hair. Large areas filled with enzyme or hormone do not exist in the pancreas. Choice 4 is incorrect as there is no layered arrangement of cells in the pancreas. So the correct answer to question is choice 2.

Front 166

The ribonucleic acid involved in protein synthesis is found primarily in the
1. nucleolus.
2. mitochondria.
3. Golgi apparatus.
4. fluid ground substance.
5. granular endoplasmic reticulum.

Back 166

The correct answer is choice 5, granular endoplasmic reticulum....... Proteins are not only a major structural component of cells but in the form of enzymes mediate every metabolic process within the cell. Protein synthesis is therefore an essential and continuous activity of all cells. The process involves the transcription of the DNA code to a messenger RNA in the nucleus which then enters into the cytoplasm to associate with ribosomes upon which protein synthesis can occur. The principal organelles are therefore the nucleus and ribosomes in which the DNA and RNA respectively are primarily found. Ribosomes are found free in the cytoplasm but the majority are found on the surface of granular endoplasmic reticulum. In summary, the ribonucleic acid, RNA, involved in protein synthesis is found primarily in the granular endoplasmic reticulum, choice 5. Nucleolus, choice 1 , found in the nucleus of some cells, is the site of ribosomal RNA synthesis. Mitochondria, choice 2, and Golgi apparatus, choice 3, are described in previous questions. The mitochondria produce ATP from glucose and other food molecules and the Golgi apparatus packages prepared proteins for secretion by the cell. Fluid ground substance, choice 4, an organic material, serves as the matrix of the extracellular material present in connective tissue. So the correct answer to question is choice 5.

Front 167

The root (radix linguae) of the tongue is connected to the hyoid bone by what two muscles?
A. Chondroglossus and Styloglossus
B. Genioglossus and Styloglossus
C. Hyoglossus and Genioglossus
D. Palatoglossus and Hyoglossus
E. Styloglossus and Palatoglossus

Back 167

The correct answer is C, hyoglossus and genioglossus..... The root (radix linguae) of the tongue is connected to the hyoid bone by the Hyoglossus and Genioglossus muscles (choice C) and the hyoglossal membrane. The Chondroglossus muscle is often considered to be part of the Hyoglossus, but is separated from it by fibers of the Genioglossus muscle. The Palatoglossus muscle is primarily associated with the soft palate and the Styloglossus muscle arises from the anterior and lateral surfaces of the styloid process.

Front 168

The roots of the brachial plexus are derived from the ventral rami of
A. the cervical plexus.
B. the spinal accessory nerve.
C. spinal nerves C3 through C5
D. spinal nerves C3 through C7.
E. spinal nerves C5 through T1.

Back 168

The correct answer is choice E, C5 to T1........ The ventral primary rami of the lower four cervical nerves and the first thoracic nerve participate in the formation of the brachial plexus. Choice A is incorrect. The cervical plexus is derived from the ventral primary rami of the first four cervical nerves. It is a somatic plexus consisting of cutaneous branches, motor branches to several neck muscles, and the phrenic nerve. Choice B is incorrect. The spinal accessory is a cranial nerve (CN XI) which includes a spinal root derived from upper cervical segments. The spinal portion is responsible for innervation of sternocleidomastoid and trapezius. Choice C is incorrect. Cervical spinal nerves 3,4 and 5 contribute to the phrenic nerve. Choice D is incorrect. Spinal nerves C3 and C4 participate in the cervical plexus. C5,6 and 7 contribute to the brachial plexus.

Front 169

The secretion of which of the following with development of the tongue EXCEPT the endocrine glands is NOT essential to life?
1. Parathyroids
2. Adrenal cortex
3. Adrenal medulla
4. Anterior pituitary
5. Pancreatic islets (Langerhans)

Back 169

The correct answer is choice 3, the adrenal medulla...... The adrenal or suprarenal medulla, which produces epinephrine and norepinephrine, is not essential to life. The parathyroids, choice 1, produce parathyroid hormone which raises blood calcium through bone resorption. Steady blood calcium level is essential. The adrenal cortex, choice 2, produces aldosterone which aids in sodium resorption, as well as I cortisone and many glucocorticoids and mineral corticoids. As these are involved in ion balance, the adrenal cortex is essential to life. Choice 4, the anterior pituitary, is the so-called master gland and, as such, controls many other glands. It produces, among other 1 hormones. GH, FSH. LH, ACTH and TSH. It is considered essential to life. The pancreatic islets produce both glucagon, which raises blood sugar, and insulin, which lowers blood sugar. Since blood sugar control is essential, the pancreas is also essential to life. So the correct answer to question is choice 3.

Front 170

The semicircular canals of the middle ear send information relating to equilibrium to which of the following nuclei of the reticular formation?
A. Interstitial nucleus
B. Nucleus ambiguus
C. Olivary nucleus
D. Solitary nucleus
E. Vestibular nucleus

Back 170

The correct answer is E, vestibular nucleus....... The vestibular nucleus (choice E) is divided into four separate subdivisions, each of which receives signals from the semicircular canals of the middle ear relating to equilibrium. These four subdivisions correct the movement of the eyes, neck, head, as well as other portions of the body. The interstitial nucleus (choice A) is responsible for only the rotational movements of the head and eyes. The nucleus ambiguus (choice B) supplies motor fibers to skeletal muscles. The olivary nucleus (choice C) is associated with the auditory pathway. The solitary nucleus (choice D) receives information on taste sensations.

Front 171

The structure first formed by the tooth bud that remains in evidence in the formed tooth is the
1. primary cuticle.
2. secondary cuticle.
3. inner enamel epithelium.
4. cementoenamel junction.
5. dentinoenamel junction

Back 171

The correct answer is choice 5, the dentinoenamel junction....... Let's review the choices briefly. The primary cuticle consists of the outer layer of enamel which is not mineralized when enamel formation is complete. Together with the nonfunctioning leftover enamel organ, they form Nasmyth's membrane which is present on the tooth surface when it erupts. Secondary cuticle, choice 2, refers to an older term for a keratinized reduced enamel epithelium prior to eruption. It will not remain after eruption. Inner enamel epithelium, choice 3, is the layer of the tooth bud that causes cells of the dental papilla to differentiate into odontoblasts. The layer itself will later become the ameloblasts and will later form enamel, and then after that, it will degenerate and sections will form the epithelial rests of Malassez. The cemento-enamel junction, choice 4, forms as cementoblasts deposit cementum on the surface of root dentin, but the CEJ is formed later than choice 5, the dentino-enamel junction. The dentino-enamel junction first forms as ameloblasts and odontoblasts begin to lay down enamel and dentin, respectively. The DEJ remains in the formed tooth and it is the first structure formed which remains in the formed tooth. So the correct answer to question is choice 5.

Front 172

The submucosa is present in each of the following EXCEPT one. Which one is this EXCEPTION?
A. Colon
B. Stomach
C. Jejunum
D. Gallbladder
E. Duodenum

Back 172

The correct answer is choice D, the gallbladder...... Note that choices A, B,C and E are all part of the alimentary canal, while choice D, the gall bladder is an accessory gland. The layers of the alimentary canal include, from the inside out, the epithelium(of various types), a lamina propria of connective tissue underneath the epithelium, the submucosa of loose connective tissue, circular and longitudinal muscle layers, and the outer loose connective tissue, the tunica adventitia(in the esophagus) or serosa (in the stomach and intestines). By contrast, the wall of the gall bladder contains epithelium, lamina propria, muscle layers, a perimuscular connective tissue layer and a serosa. Note that no submucosal layer is found in the gallbladder. The correct answer to question is choice D.

Front 173

The superior and inferior ophthalmic veins drain directly or indirectly into the
A. frontal vein.
B. cavernous sinus.
C. anterior facial vein.
D. internal jugular vein.
E. superior petrosal sinus.

Back 173

The correct answer is choice B, the cavernous sinus....... The ophthalmic veins join the sphenoparietal sinus which travels along the lesser wing of the sphenoid to form the cavernous sinus. Choice A is incorrect. The frontal vein, when present, is a tributary of the superior ophthalmic vein. Choice C is incorrect. Anterior facial vein is archaic terminology for the facial vein, which begins as the angular vein at the side of the nose and terminates by joining the anterior limb of the retromandibular vein to form the common facial vein. Choice D is incorrect. The internal jugular vein is the direct continuation of the sigmoid sinus. It receives the inferior petrosal sinus directly. Choice E is incorrect. The superior petrosal sinus, along with the inferior petrosal sinus, drains the cavernous sinus posteriorly.

Front 174

The superior laryngeal artery pierces the thyrohyoid membrane in company with which of the following laryngeal nerves?
A. lnferior laryngeal
B. Internal laryngeal
C. External laryngeal
D. Superior laryngeal
E. Recurrent laryngeal

Back 174

The correct answer is choice B, the internal laryngeal nerve..... The internal laryngeal nerve, a purely sensory branch of the superior laryngeal branch of the vagus, pierces the thyrohyoid membrane to supply the mucosa of the larynx above the vocal folds. Choice A is incorrect. The inferior laryngeal nerve is the terminal portion of the recurrent laryngeal nerve. It enters the larynx by passing deep to the inferior border of the inferior constrictor muscle, along with the inferior laryngeal artery. Choice C is incorrect. The external laryngeal nerve does not supply the interior of the larynx. It innervates the cricothyroid muscle. Choice D is incorrect. The superior laryngeal nerve divides to form the internal and external laryngeal nerves. Choice E is incorrect. The recurrent laryngeal nerve is a mixed nerve which supplies all intrinsic laryngeal muscles except cricothyroid, and conveys sensation from the laryngeal mucosa below the vocal folds. Its terminal portion is the inferior laryngeal nerve.

Front 175

The temporalis muscle inserts into the
A. coronoid process.
B. condylar process.
C. fovea of the mandible.
D. lateral aspect of the mandibular angle.
E. articular disk of the temporomandibular joint.

Back 175

The correct answer is choice A, the coronoid process......
The fibers of temporalis converge to a tendon which inserts primarily on the coronoid process of the mandible. Choice B is incorrect. The condylar process, or head and neck of the mandible, is the site of insertion of the lateral pterygoid muscle. Choice C is incorrect. Most of the fibers of the lateral pterygoid muscle insert into the depression on the neck of the mandible known as the fovea. Choice D is incorrect. The masseter inserts on the lateral aspect of the ramus of the mandible, including its angle. Choice E is incorrect. The lateral pterygoid may contain fibers which insert directly into the articular disk.

Front 176

The tendon of the tensor veli palatini muscle curves around the
1. angular spine.
2. styloid process.
3. pterygoid hamulus.
4. lateral pterygoid plate.
5. spine of the sphenoid.

Back 176

The correct answer is choice 3, the pterygoid hamulus...... The tensor veli palatini muscle arises from the sphenoid bone and from the lateral surface of the auditory tube. It inserts into the aponeurosis of the soft palate and onto the posterior edge of the bony hard palate. The tensor veli palatini curves around the pterygoid hamulus, choice 3, before reaching its final insertion pulling the soft palate laterally when it contracts. This prevents the passage of a bolus of food from forcing the soft palate upwards into the nasal part of the pharynx. The tensor veli palatini is innervated by the motor division of the trigeminal nerve. So the correct answer to question is choice 3.

Front 177

The thick myofilaments observed in transmission electron microscopic preparations of skeletal muscle are
1. composed mainly of actin.
2. present only in the A band.
3. present in both A and I bands.
4. traversed or crossed by the Z band.

Back 177

The correct answer is choice 2, present only in the A band....... It will be helpful to review a diagram from your home study notes or your text when checking this question. A-bands consist of thick myofilaments made up of myosin. I-bands consists of thin myofilaments made up of actin. I-bands, or actin filaments, connect to Z-lines or bands. So choice 2 is correct. Choice 1 is incorrect because thick myofilaments are myosin, not actin. Choice 3 is incorrect because I-bands consist of only actin, not myosin. Choice 4 is incorrect because only actin I-bands join the Z-band. Myosin A-bands do not connect to the Z-band. So the correct answer to question is choice 2.

Front 178

The thoracic duct empties directly into the junction of the
A. superior vena cava and the azygos vein.
B. left jugular and brachiocephalic veins.
C. right jugular and brachiocephalic veins.
D. left internal jugular and subclavian veins.
E. right internal jugular and subclavian veins.

Back 178

The correct answer is choice D, the left jugular and subclavian veins...... The thoracic duct terminates at the beginning of the left brachiocephalic vein (junction of left internal jugular and subclavian veins). Choice A is incorrect. The azygos vein arches over the root of the right lung to empty into the superior vena cava before it enters the right atrium. Choice B is incorrect. The external jugular vein terminates by joining the subclavian vein. Choice C is incorrect. Choice E is incorrect. The right lymphatic duct terminates by joining the junction of the right internal jugular and right subclavian veins. It drains lymph from the upper right quadrant of the body, and may also drain a portion of the left lung.

Front 179

The three divisions of the trigeminal nerve pass through openings in which of the following bones?
A. Frontal
B. Sphenoid
C. Temporal
D. Parietal
E. Occipital

Back 179

The correct answer is choice B, the sphenoid bone...... Superior orbital fissure is located between the greater and lesser wings of the sphenoid. Foramen rotundum and foramen ovale are found in the greater wing. Choice A is incorrect. The frontal bone forms much of the floor of the anterior cranial fossa. Choice C is incorrect. The temporal bone contains the internal auditory meatus. which transmits CN's VII and VIII. Choice D is incorrect. The parietal bone does not contribute to the floor of the cranial cavity. Choice E is incorrect. The occipital bone forms much of the floor of the posterior cranial fossa. It contains foramen magnum and the hypoglossal canal, and forms a boundary of the jugular foramen, which transmits CN's IX, X, and XI and the internal jugular vein.

Front 180

The trigeminal nerve innervates exclusively which of the following muscles or muscle parts?
A. Buccinator and masseter
B. Mylohyoid and geniohyoid
C. Medial and lateral pterygoid
D. Tensor and levator veli palatini
E. Anterior and posterior bellies of digastric

Back 180

The correct answer is choice C, the medial and lateral pterygoids.......
The medial and lateral pterygoid muscles are two of the four muscles of mastication, which are derived from the first pharyngeal arch. The nerve of the first (mandibular) arch is V3, the mandibular nerve. Choice A is incorrect. Buccinator is a muscle of facial expression, derived from the third pharyngeal arch. It is supplied by CN VII. Masseter is supplied by V3. Choice B is incorrect. Mylohyoid is supplied by V3. Geniohyoid is supplied by a branch of cervical nerve IX which also supplies thyrohoid. Choice D is incorrect. The tensor veli palatini is supplied by V3. Levator palati is supplied by a motor branch of pharyngeal plexus, which is derived from CN X and the cranial portion of CN XI. Choice E is incorrect. Anterior belly of digastric is supplied by V3. Posterior belly is supplied by CN VII

Front 181

The unpaired vessels contributing to the arterial circle of the brain include the
1. internal carotid and vertebral arteries.
2. posterior and anterior cerebral arteries.
3. anterior cerebral and anterior communicating arteries.
4. anterior cerebral and posterior communicating arteries.
5. anterior communicating and basilar arteries

Back 181

The correct answer is choice 5, the anterior communicating and basilar arteries...... The arterial circle of the brain, also known as the circle of Willis, is formed by the carotid and vertebral arteries anastomosing with each other on the ventral surface of the brain stem. It consists of seven vessels: a pair of anterior cerebral arteries, a branch of the anterior communicating artery unpaired, a pair of posterior communicating branches and a pair of posterior cerebral arteries. It also receives contribution from the basilar artery which is unpaired. Therefore, the unpaired vessels that contribute to the circle of Willis include the anterior communicating artery and the basilar artery choice 5. Choice 1, the internal carotid and vertebral arteries are both paired. Choice 2, the posterior and anterior cerebral arteries are both paired. Choice 3, the anterior cerebral arteries are paired and the anterior communicating artery is single and unpaired. Choice 4, the anterior cerebral and posterior communicating arteries are both paired. So the correct answer to question is choice 5.

Front 182

The vagus nerve supplies parasympathetic fibers to which of the following?
A. Descending colon
B. Ascending colon
C. Sigmoid colon
D. Rectum
E. Anus

Back 182

The correct answer is choice B, the ascending colon...... The ascending colon is part of the midgut, which extends from the hepatic diverticulum to the junction of the proximal two-thirds and distal one-third of the transverse colon. All structures derived from midgut and foregut receive preganglionic parasympathetic innervation from the vagus. Choice A is incorrect. The descending colon is derived from embryonic hindgut. which receives preganglionic parasympathetic innervation from pelvic splanchnic nerves (S2, S3, and S4). Choice B is incorrect. Sigmoid colon is derived from embryonic hindgut. Choice C is incorrect. The upper part of the rectum is derived from hindgut. The lower portion is derived from the embryonic cloaca1 region. Choice E is incorrect. The anus is innervated by the inferior rectal branch of the pudendal nerve. This is a somatic nerve.

Front 183

The vertebral artery is a branch of the
A. brachiocephalic artery.
B. external carotid artery.
C. internal carotid artery.
D. subclavian artery.
E. thyrocervical trunk.

Back 183

The correct answer is choice D, the subclavian artery...... The vertebral artery is the largest branch of the first portion of the subclavian artery. It enters foramen magnum to supply the brainstem. Choice A is incorrect. The brachiocephalic artery (trunk) normally has no branches other than its terminal branches, the right subclavian and the right common carotid arteries. Choice B is incorrect. The external carotid artery has branches which supply structures of the neck and face. Choice C is incorrect. The internal carotid artery has no branches in the neck. Choice E is incorrect. The thyrocervical trunk is a branch of the subclavian artery which supplies the thyroid gland and structures of the neck and shoulder regions.

Front 184

The visceral and parietal pericardia are continuous at the
1. pulmonary artery only.
2. inferior vena cava only.
3. veins and arteries entering and leaving the heart.

Back 184

The correct answer is choice 3, the veins and arteries entering and leaving the heart...... The pericardium is a fibroserous sac surrounding the heart and the beginning of the great vessels. It consists of a strong outer fibrous layer and a relatively thin inner serous layer. This serous layer is again subdivided into two layers, the visceral on the heart and the parietal on the fibrous portion of the pericardium. These layers are continuous with one another along a line running from the inferior vena cava, right pulmonary veins, superior vena cava and left pulmonary veins at one end and the aorta and pulmonary trunk at the other end. So the correct answer to question is choice 3.

Front 185

The white pulp of the spleen is composed primarily of
1. sinusoids.
2. macrophages.
3. lymphocytes.
4. connective tissue.

Back 185

The correct answer is choice 3, lymphocytes...... The spleen is a large lymphoid organ responsible for the removal of particulate matter from circulating blood, production of immunological responses against blood-borne antigens and removal of aged or defective blood cells from the circulation. Structurally, the spleen is composed of an outer capsule surrounding lymphoid tissues, known as the white pulp separated by blood-filled sinuses known as the red pulp. The white pulp is composed primarily of lymphocytes, choice 3. So the correct answer to question is choice 3.

Front 186

The zona glomerulosa of the adrenal cortex produces which of the following?
A. Aldosterone
B. Cortisol
C. Epinephrine
D. Progesterone
E. Somatostatin

Back 186

The correct answer is A, aldosterone........ The adrenal cortex is composed of three relatively distinct layers: zona glomerulosa, zona fasciculata, and zona reticularis. The zona glomerulosa of the adrenal cortex secretes aldosterone (choice A). The zona fasciculata and zona reticularis secrete cortisol (choice B) and several other glucocorticoids. Epinephrine (choice C) is produced by the adrenal medulla. Progesterone (choice D) is secreted by the corpus luteum of the ovaries and somatostatin (choice E) is produced by the pancreas

Front 187

The zona pellucida is associated with which of the following?
1. Corpus luteum
2. Corpus albicans
3. Oocyte in a mature follicle
4. Oocyte in an early primary follicle

Back 187

The correct answer is choice 3, an oocyte in a mature follicle....... With the onset of puberty, a number of primordial follicles begin to mature with each ovarian cycle. The ovocyte is an early primary follicle, choice 4. It undergoes several important changes as it matures. It begins to increase in size. The surrounding epithelial cells, the follicle cells, change from flat to cuboidal and a layer of acellular material is deposited on the surface of the ovocyte. This material which is produced by the follicular cells as well as the oocyte gradually increases in thickness forming the zona pellucida present in a mature follicle of the oocyte, choice 3. The corpus luteum, choice 1, is formed by the luteal cells following ovulation and secretes progesterone. The corpus albicans, choice 2, is a mass of fibrotic scar tissue and it is formed by the degeneration of the corpus luteum when fertilization fails to occur. So the correct answer to question is choice 3.

Front 188

The zona reticularis is the inner layer of the
1. cortex of the thymus.
2. medulla of the thymus.
3. cortex of the suprarenal (adrenal).
4. medulla of the suprarenal (adrenal).

Back 188

The correct answer is choice 3, cortex of the suprarenal (adrenal)....... The zona reticularis is the innermost layer of the cortex portion of the suprarenal glands, choice 3. The suprarenal glands are a pair of small yellowish brown bodies lying on the medial pan of the superior end of each kidney. The suprarenal glands are also known as the adrenal glands. These glands are essential for the secretion of imponant hormones including aldosterone. cortisone, adrenaline, and noradrenaline. Each gland is divided into two distinct parts, an outer cortex and an inner medulla. The outer cortex is further subdivided into three layers, the zona glomerularosa, the zona fasiculata and the zona reticularis, with the zona reticularis as the innermost layer. So the correct answer to question is choice 3.

Front 189

Tropocollagen is a protein molecule found in
1. collagen and elastic fibers only.
2. elastic and reticular fibers only.
3. collagen and reticular fibers only.
4. collagen, elastic and reticular fibers.

Back 189

The correct answer is choice 3, collage and reticular fibers....... Tropocollagen is the name for the 3-polypeptide chain molecule often referred to just as collagen. Collagen is found of course, in collagen fibers. It is also found in reticular fibers. However, collagen is not found in elastic fibers. Elastic fibers are composed of the protein elastin which is notable for the presence of amino acids, desmosine and isodesmosine. By contrast, collagen contains the unusual amino acids, hydroxyproline and hydroxylysine. So the correct answer to question is choice 3.

Front 190

Uniform growth in the infolding portion of an epithelial root sheath (Hertwig) results in formation of a
1. single-rooted tooth.
2. double-rooted tooth.
3. three-rooted tooth.
4. tooth without a root.

Back 190

The correct answer is choice 1, single rooted tooth..... Hertwig's epithelial root sheath formed by the enamel organ molds the shape of the roots. Prior to the beginning of root formation, the root sheath forms the epithelial diaphragm. Uniform growth in the infolding portion of the sheath, the epithelial diaphragm, will result in the formation of a single rooted tooth, choice 1. Invaginations along with differential growth of the epithelial diaphragm will result in a multirooted tooth, choices 2 and 3. Malformation or the absence of the Hertwig's epithelial root sheath can result in a tooth without a root, choice 4. So the correct answer to question is choice 1.

Front 191

Variation of the size of the lumen of the bronchiole during inspiration and expiration is caused primarily by
1. striated muscle and cartilage.
2. smooth muscle and elastic fibers.
3. the basement membrane and collagen fibers.
4. areolar connective tissue and cartilage.

Back 191

The correct answer is choice 2, smooth muscle and elastic fibers...... Respiratory bronchioles, the smallest units of the bronchopulmonary system, are short, smooth muscle tubes without cartilage. During inspiration and expiration, the bronchiole expands and contracts with its smooth muscle walls and supporting reticular a d elastic fibers. The other answer choices are incorrect because they contain cartilage or striated muscle. both of which are not contained in the bronchiole. Choice 3 is incorrect because the basement membrane and collagen fibers would not be able to vary in size since they cannot contract. So the correct answer to question is choice 2.

Front 192

What layer of the epidermis is composed of multilaminar cuboidal-like cells that are bound together by means of numerous cytoplasmic extensions and desmosomal junctions?
A. Stratum basale
B. Stratum corneum
C. Stratum granulosum
D. Stratum lucidum
E. Stratum spinosum

Back 192

The correct answer is E, the stratum spinosum...... The epidermis is the outermost layer of the integument. The layers of the epidermis from deep to superficial can be remembered with the following mnemonic: BiG Stars Give Lots of Charity; Stratum Basale (Germinativum), Spinosum, Granulosum, Lucidum, Corneum. The stratum spinosum (choice E) is a layer of the epidermis composed of multilaminar cuboidal-like cells that are bound together by means of numerous cytoplasmic extensions and desmosomal junctions. The stratum basale (choice A) is a proliferative basal layer of columnar-like cells that contain the fibrous protein keratin. The stratum corneum (choice B) is the outermost layer of the epidermis. This layer consists of many layers of flat, anucleated and keratinized cells. The stratum granulosum (choice C) consists of flat polygonal cells filled with basophilic keratohyalin granules. The stratum lucidum is a thin layer of cells located between the stratum granulosum and stratum corneum.

Front 193

When a tooth first erupts into the oral cavity, the attachment epithelium is derived from
1. oral mucosa.
2. reduced enamel epithelium.
3. epithelial rests of Malassez.
4. the epithelial root sheath (Hertwig).

Back 193

The correct answer is choice 2, reduced enamel epithelium..... When the cusps of the tooth emerge from the gingiva, the reduced enamel epithelium fuses with the gingival epithelium and, together with the primary cuticle or last cell layer of enamel, forms the epithelial attachment. The reduced enamel epithelium is tbe name for the combination of ameloblasts, stellate reticulum and outer enamel epithelium which remain after tooth formation is complete. Choice 3 is incorrect. The epithelial rests of Malassez are epithelial remnants of the epithelial sheath of Hertwig, choice 4. This sheath causes differentiation of odontoblasts to form root dentin and is composed of both inner and outer enamel epithelium. So the correct answer to question is choice 2.

Front 194

Which group of fibers of the periodontal ligament is the first to offer resistance to movement of the tooth in an occlusal direction?
A. Alveolar crest
B. lnterradicular
C. Horizontal
D. Oblique
E. Apical

Back 194

The correct answer is choice E, apical fibers...... From the coronal down to the apical, the periodontal fiber groups are: the alveolar crest fibers, slanted upward and coronally from alveolar crest to CEJ, then horizontal fibers from cementum horizontally to alveolar bone, then oblique fibers slanting downward and apically from alveolar bone to cementum, then apical fibers, connecting vertically from the apical part of the bony socket to the apex of the root. Because of their vertical position and attachment at the base of the root, these fibers are the first to resist an upward (occlusal, coronal) motion of the tooth. The correct answer to question is choice E.

Front 195

Which of the following are mobilized when a cell produces an excessive amount of protein?
1. Lysosomes
2. Mitochondria
3. Lipofuscin granules
4. Rough endoplasmic reticula
5. All of the above

Back 195

The correct answer is choice 1, lysosomes....... Apparently, the question is referring to the method by which a cell can rid itself of excessive protein that it has produced. In this case, choice 1 is the logical answer, as lysosomes contain proteolytic enzymes capable of digesting cellular proteins. Choice 4 may come to mind because the proteins are produced by ribosomes of the rough endoplasmic reticulum. However, the question is referring to what occurs after these proteins are made. Choice 2 is incorrect because mitochondria produce ATPs from the oxidation of glucose. Choice 3 is incorrect. Lipofuscin granules refers to a fatty proteinaceous material that accumulates in older cells as a result of the action of lysosomes on cell materials. So the correct answer to question is choice 1.

Front 196

Which of the following are pure serous glands?
A. Sublingual glands
B. Glands of Brunner
C. Submandibular glands
D. Glands of von Ebner
E. Glands of Blandin-Nuhn

Back 196

The correct answer is choice D, glands of von ebner....... Lets review the serous/mucous content of the salivary glands. The largest gland, the parotid, is primarily, but not wholly, serous. (In infants, some mucous secretion is produced). Both the submandibular and sublingual are mixed serous/mucous, although the submandibular is primarily serous while the sublingual is primarily mucous. On the tongue, Von Ebner's glands are found in the area surrounding the vallate papillae. These glands are serous only. Other lingual glands are known as anterior lingual or Blandin-Nuhn glands. They are mixed, but primarily mucus. Labial and buccal glands are usually mixed glands. Brunners glands are found in the villi of the small intestine. So our correct answer to question is choice D.

Front 197

Which of the following arteries does NOT accompany the corresponding nerve throughout its course?
1. Lingual
2. lnfraorbital
3. Inferior alveolar
4. Posterior superior alveolar

Back 197

The correct answer is choice 1, the lingual artery...... The lingual artery is the main source of blood to the tongue and is a branch of the external carotid. The innervation of the tongue is supplied by the lingual branch of the mandibular nerve of the trigeminal for sensation to the anterior two-thirds; the chorda tympani, a branch of cranial nerve 7, for taste to the anterior two-thirds: the lingual branch of the glossopharyngeal nerve, cranial nerve 9, to the posterior one-third; and the superior laryngeal nerve of the vagus to the circumvallate papillae. None of these nerves travels completely with the lingual artery. Choice 2 is incorrect. The infraorbital nerve and artery travel together through the infraorbital foramen to the face below the orbit and to the anterior maxillary teeth. Choice 3 is incorrect. The inferior alveolar nerve and artery travel through the mandibular canal together to the mandibular teeth. The inferior alveolar artery is a branch of the maxillary artery. The posterior superior alveolar nerve and artery also travel together and the artery is also a branch of the maxillary artery. This artery and nerve supply the maxillary molar teeth. So the correct answer to question is choice 1.

Front 198

Which of the following arteries is NOT a branch of the maxillary artery?
1. Deep temporal
2. Middle meningeal
3. Inferior alveolar
4. Superficial temporal
5. Posterior superior alveolar

Back 198

The correct answer is choice 4, the superficial temporal..... The maxillary artery, the terminal branch of the external carotid, gives off many branches. These include the deep temporal, choice 1, the middle meningeal, choice 2, the inferior alveolar, choice 3, and the posterior superior alveolar, choice 5. Only the superficial temporal, choice 4, is not a branch of the maxillary artery. It is actually a terminal branch of the external carotid. So the correct answer to question is choice 4.

Front 199

Which of the following BEST characterizes the alveolar mucous membrane?
A. Has no melanocytes
B. Firmly bound to underlying bone
C. Well developed epithelial ridges
D. Separated from the gingiva by the free gingival groove
E. Appears red due to high vascularity and thinness of epithelium

Back 199

The correct answer is choice E, appears red due to high vascularity and thinness of epithelium.... Alveolar mucosa is a loosely bound non-keratinized epithelium of stratified epithelium above a lamina propria, with a submucosal layer. This is unlike the gingiva and epithelial tissue covering the hard palate, whih is tightly bound, keratinized and does not possess a submucosal layer. Melanocytes can be present in alveolar mucous membrane, and many dark-skinned people have darkly pigmented gingiva and oral mucosa. Well developed epithelial ridges are not found in alveolar mucous membrane. The gingiva is separated from the alveolar mucosa by the mucogingival junction. The free gingival groove marks the end of free gingiva, and the beginning of the attached gingiva. So, choices A,B,C, and D are all incorrect. Choice E is correct. Thin, non keratinized epithelium overlying a rich blood supply will appear red. Our correct answer to question is choice E.

Front 200

Which of the following BEST describes the passage of material through the hepatic sinusoids?
A. Blood passes toward the central vein.
B. Bile passes peripherally toward the portal canal.
C. Lymph moves centrally to join the sublobular duct.
D. Lymph moves peripherally toward the space of Disse.
E. Blood passes peripherally away from the central vein.

Back 200

The correct answer is choice A. Blood from branches of the portal vein(nutrient rich) and hepatic artery(O2 rich) enters the liver sinusoids at the periphery of the liver lobule, and passes centripetally to reach the central vein. Choice B is incorrect. Bile is excreted by hepatocytes into radicles of the bile duct system. Choice C is incorrect. Lymphatic vessels of the liver lead to larger vesssels in the pona hepatis and enter hepatic nodes. Choice D is incorrect. The space of Disse separates the hepatocyte from the sinusoidal vessel. It is not a lymphatic channel. Choice E is incorrect. Blood passes centripetally towards the central vein of the liver lobule.

Front 201

Which of the following blood elements is a fragment of megakaryocytic cytoplasm?
1. Platelet
2. Normoblast
3. Erythrocyte
4. Promyelocyte
5. Proerythroblast

Back 201

The correct answer is choice 1. Platelets are formed in the red bone marrow and to a small extent in the spleen by fragmentation of very large cells known as megakaryocytes. These megakaryocytes have large multilobed nuclei of varied shapes. Choice 2, normoblast, is incorrect. Normoblasts are a precursor stage of erythrocytes or red blood cells. Choice 3 is incorrect. Erythrocytes or red blood cells form by erythropoiesis in the red bone marrow from nucleated cells known as hemocytoblasts or stem cells. Choice 4 is incorrect. Promyelocytes are precursor cells of the granulocytes: the neutrophils, basophils and eosinophils. Choice 5 is incorrect. A proerythroblast is another precursor cell of erythrocytes or red blood cells. So the correct answer to question is choice 1.

Front 202

Which of the following branches of the axillary artery usually supplies the latissimus dorsi muscle?
1. Thoracodorsal
2. Thoracoacromial
3. Lateral thoracic
4. Circumflex scapular
5. Posterior humeral circumflex

Back 202

The correct answer is choice 1. The latissimus dorsi muscle is a very broad, flat triangular muscle in the lower part of the back which is overlapped by the lower part of the trapezius muscle. It is innervated by the thoracodorsal nerve, a branch of the brachial plexus. The blood is supplied by the thoracodorsal artery, choice 1, a branch of the subscapular from the axillary artery. The thoracoacromial artery, choice 2, a branch of the axillary artery gives off branches that supply the deltoid, pectoralis major and minor and the subclavius muscles. The lateral thoracic, choice 3, also a branch of the axillary artery, primarily supplies the mammary glands. The circumflex scapular artery, choice 4, a branch of the subscapular off the axillary artery, curves around the scapular and anastomoses with the suprascapular and dorsal scapular aneries. The posterior humeral circumflex artery, choice 5, branches off the lower part of the axillary artery and anastomoses with the anterior humeral circumflex artery, also a branch of the axillary artery. So the correct answer to question is choice 1.

Front 203

Which of the following cells is most likely to have an abundant amount of rough-surfaced endoplasmic reticulum?
1. Osteocyte
2. Macrophage
3. Osteoblast
4. Mesothelial cell
5. Small lymphocyte

Back 203

The correct answer is choice 3. This is really an indirect question about the function of cell organelles. Rough-surfaced endoplasmic reticulum produces proteins for export out of the cell. The rough surface is lined with ribosomes which produce proteins. Choice 1, osteocytes, are mature bone cells living within already-formed bone and do not produce large quantities of protein for export. Choice 2, macrophages, are primarily involved in ingesting foreign material and are involved in immune respose. They do not produce large quantities of export protein. Choice 3, osteoblasts, is correct. Osteoblasts are bone-forming cells which lay down bone matrix which is primarily protein. Choice 4, mesothelial cells, are lining cells inside blood vessels. They do not produce large amounts of export protein. Choice 5, lymphocytes, is also incorrect. Lymphocytes, involved primarily in immune response, do not produce large quantities of export protein. It should be noted that if lymphocytes become plasma cells -- in particular, B lymphocytes when they differentiate into plasma cells -- then large quantities of antibodies would be produced. However, we're talking here about lymphocytes, so the correct answer to question is choice 3.

Front 204

Which of the following branches of the external carotid artery originates just below the level of the hyoid bone's greater cornu?
1. The facial artery
2. The occipital artery
3. The maxillary artery
4. The superior thyroid artery
5. The posterior auricular artery

Back 204

The correct answer is choice 4.
The external carotid anery extends from the upper border of the thyroid cartilage to the back of the neck of the mandible where it ends by dividing into the superficial temporal and maxillary artery. Eight branches arise from the external carotid artery. Only the superior thyroid artery, choice 4, originates just below the tip of the greater horn of the hyoid bone and runs downwards to the thyroid gland. The facial artery, choice 1 , arises immediately above the lingual and ends at the medial angle of the eye. Thc occipital artery, choice 2, originates opposite the facial artery and ends near the medial end of the occipital bone. The maxillary artery, choice 3, beglns between the parotid gland and the back of the neck of the mandible and ends in the pterygopalatine fossa. The posterior auricular artery, choice 5, arises just above the posterior belly of the digastric and runs into the internal space between the mastoid process and the auricle. So the correct answer to question is choice 4.

Front 205

Which of the following cranial nerves contain parasympathetic preganglionic fibers?
A. II, III, IV, and V
B. III, IV, V, and VI
C. III, V, VII, and IX
D. III, VII, IX, and X
E. VII, IX, X, and XI

Back 205

The correct answer is choice D. CN's III, VII, IX and X are the only cranial nerves which contain preganglionic parasympathetic fibers, which synapse in the four parasympathetic ganglia of the head, or (in the case of CN X), in thoracic and abdominal nerve plexuses. Choice A is incorrect. Only CN III contains preganglionic parasympathetic fibers, which synapse in the ciliary ganglion. Choice B is incorrect. Only CN III contains preganglionic parasympathetic fibers. Choice C is incorrect. Although CN V distributes postganglionic fibers which have synapsed in the four parasympathetic ganglia of the head (ciliary, pterygopalatine, submandibular and otic), it is not considered a parasympathetic nerve because it contains no preganglionic fibers. Choice E is incorrect. CN XI, the spinal accessory, is a motor nerve which supplies trapezius and sternocleidomastoid.

Front 206

Which of the following empty into the right atrium?
1. The pulmonary and bronchial veins
2. The coronary sinus and pulmonary veins
3. The superior and inferior venae cavae and coronary sinus
4. The superior vena cava, coronary sinus, and hemiazygos vein

Back 206

The correct answer is choice 3. The heart is divided into right and left sides, each of which is composed of two chambers, an atrium and a ventricle. The right atrium has the thinnest walls of the four chambers. It receives deoxygenated blood from the superior vena cava, inferior vena cava, coronary sinus and anterior cardiac veins. This corresponds to answer choice 3. So the correct answer to question is choice 3.

Front 207

Which of the following explains why the Barr body found in certain epithelial cells is significant?
A. It suggests mitotic activity.
B. It indicates protein synthesis.
C. It indicates a metaplasmic change.
D. It is a symptom of nuclear disintegration.
E. It assists in differentiating between the sexes.

Back 207

The correct answer is choice E. The Barr body is useful in determining the sex of a cell. In certain epithelial cells, the presence of the Barr body indicates a female cell, while its absence indicates a male cell. During interphase, one X chromosome remains condensed as a dark staining body near the nuclear membrane. One X chromosome does not take this form. Since only the female has two X chromosomes, only the female can have a Barr body. The Barr body can be used in identifying the genetic sex of an individual, and has been used, for example, in the Olympics, to ensure the accurate sex of the participants. The correct answer to question is choice E.

Front 208

Which of the following features distinguishes bone from osteoid?
A. Bone is not resorbed.
B. Bone has a mineralized matrix.
C. Osteoid contains fewer lacunae per unit area.
D. Osteoid contains a different type of fiber in its matrix.

Back 208

The correct answer is choice B. Osteoid is uncalcified bone matrix. Small temporary areas of osteoid are part of the normal bone-forming process. Large abnormal areas may be present in diseases such as rickets. Osteoid contains matrix fibers but no calcium phosphate mineral salts. Looking at the other choices, A is incorrect because mature bone is constantly resorbed and remodeled by osteoclasts and osteoblasts. C is incorrect because the number of lacunae, with trapped osteocytes, is determined once the unmineralized matrix is set down, so that bone and osteoid have the same number of lacunae. D is incorrect as the only change that occurs to osteoid matrix is mineralization. No fiber change occurs. So the correct answer to question is choice B.

Front 209

Which of the following forms of connective tissues has a preponderance of amorphous ground substance over fibers?
1. Loose
2. Cartilage
3. Reticular
4. Dense, regularly arranged
5. Dense, irregularly arranged

Back 209

The correct answer is choice 2. Connective tissue usually contains fibers, often of collagen, and ground substance which is an amorphous material surrounding the fibers. In particular, loose connective tissue (choice 1) is stretchable and contains collagenous and elastic fibers and hyaluronic acid ground substance. Choice 2, cartilage, our correct choice, contains fibers of collagen or elastic, but a much greater percentage of ground substance than found in the other connective tissues. Choice 3, reticular connective tissue, is primarily fibrous; in particular, reticular fibers. It is found in lymph nodes and spleen and does not contain much ground substance. Dense connective tissues, choices 4 and 5, consist primarily of collagenous or elastic fiber bundles with only smaller amounts of fluid matrix. Dense connective tissue comprises tendons and ligaments. So the correct answer to question is choice 2.

Front 210

Which of the following glands stimulates osteoclast activity?
A. Anterior pituitary
B. Hypothalamus
C. Pancreas
D. Parathyroid
E. Thyroid

Back 210

The correct answer is D. Osteoclasts are large, motile multinucleated cells found on bone surfaces at sites of resorption. When stimulated by parathyroid hormone produced in the parathyroid gland (choice D), osteoclasts increase blood calcium levels by the resorption of bone tissue. The anterior pituitary (choice A) produces various hormones, such as growth hormone, prolactin, adrenocorticotropin hormone, thyroid stimulating hormone, luteinizing hormone and follicle stimulating hormone, all of which do not affect blood calcium levels. The hypothalamus (choice B) produces hormones that lead to increased uterine contraction and water reabsorption in the kidney. The pancreas (choice C) is primarily involved with regulating blood glucose levels. The thyroid (choice E) produces calcitonin which lowers blood calcium levels.

Front 211

Which of the following groups of periodontal ligament fibers has a cementum-to cementum attachment?
1. Oblique
2. Transseptal
3. Free gingival
4. lnterradicular
5. Dentoalveolar crest

Back 211

The correct answer is choice 2. Transseptal fibers are fibers of the periodontal ligament which extend from the cementum of one tooth above the alveolar crest to the cementum of an adjacent tooth. Oblique fibers, choice 1, extend from cementum to alveolar a bone as do dental alveolar fibers, choice 5. Free gingival fibers (choice 3) attach to the tooth cementum and extend out into the gingival tissue. Choice 4, interradicular fibers, connect from cementum to bone in multi-rooted teeth. So the correct answer to question is choice 2.

Front 212

Which of the following is derived from ectomesenchyme?
A. Ameloblasts
B. Odontoblasts
C. Stellate reticulum
D. Stratum intermedium
E. Reduced enamel epithelium

Back 212

The correct answer is choice B. This is a case of "one of these things is not like the others". Note that all of the choices except B are related to enamel formation, and enamel is derived from ectodermal tissue of neural crest origin. Only odontoblasts, which form dentin, are not from this origin. Odontoblasts, as well as the pulp and the dental papilla from which they form, are of mesenchymal(and therefore mesodermal) origin. Don't be fooled by the "ecto" in ectomesenchyme. Mesenchyme is still mesodermal tissue. The correct answer to question is choice B.

Front 213

Which of the following is located at the opening between the small and the large intestines?
1. The cardiac sphincter
2. The pyloric sphincter
3. The ileocecal valve
4. The tricuspid valve

Back 213

The correct answer is choice 3. The cardiac sphincter, choice 1, is located between the inferior end of the esophagus and the stomach. The smooth muscle of this junction is continuous with that of the stomach and the muscle is not considered a true structural sphincter. The pyloric sphincter, choice 2, is located between the pyloric end of the stomach and the duodenum. While it does not control the rate of stomach emptying, it does however control the size of the particle that enters the duodenum. The ileocecal valve, choice 3, guards the opening into the cecum, the anterior portion of the large intestine, from the ileum, the posterior portion of the small intestine. It functions as an impediment to regurgitation of the cecal contents into the ileum. The tricuspid valve, choice 4, transmits blood from the right atrium of the heart to the right ventricle. It also prevents regurgitation of blood back into the right atrium during ventricular systole. So the correct answer to question is choice 3.

Front 214

Which of the following is necessary for cementum to be deposited during tooth development?
1. The tooth must be erupting.
2. A bony socket must develop.
3. An apical vascular plexus must be present.
4. The continuity of the root sheath (Hertwig) must be broken.

Back 214

The correct answer is choice 4. Root development is begun by the Hertwig root sheath which consists of inner and outer enamel epithelium. This root sheath causes dental papilla tissue to differentiate into odontoblasts and then lay down root dentin. The root sheath is then broken down as connective tissue elements form the fibers of the periodontal ligament. The remaining cells of the dental sac will then form cementum and alveolar bone. The leftover root sheath cells will become epithelial rests of Mallasez. The cementum deposition does not depend on tooth eruption (choice 1) or bony socket development (choice 2) or the presence of a vascular plexus at the root apex (choice 3). So the correct answer to question is choice 4.

Front 215

Which of the following is surrounded partly by connective tissue and epithelium, contains lymphoid follicles, has no sinuses, and is penetrated by a number of crypts?
A. Spleen
B. Thymus
C. Lymph node
D. Palatine tonsil
E. Bursa of Fabricius

Back 215

The correct answer is choice D.
The palatine tonsil is a lymphoid organ which forms a ring in the pharynx, between the glossopalatine and pharyngopalatine arches. It consists of blind sacs, or crypts which are composed of epithelial tissue overlying thin connective tissue. They may contain lymphocytes and polymorphonucleocytes. Their exact protective function is not known, but the tonsils are protective against microorganisms. The spleen has lymphoid follicles, as well as sinuses(in the red pulp), but does not contain crypts. The thymus also contains lymphoid follicles, with great numbers of lymphocytes surrounded by conective tissue, but lacks crypts. The lymph node contains filtering lymph sinuses with macrophages and reticular cells, but does not contain crypts. The Bursa of Fabricius is an organ in birds where B lymphocytes become specialized. It does not exist in humans. So the correct answer to question is choice D.

Front 216

Which of the following layers is totally lacking in thin skin?
1. Stratum corneum
2. Stratum lucidum
3. Stratum spinosum
4. Stratum germinativum

Back 216

The correct answer is choice 2. The skin, or integument, is the largest organ of the body constituting almost one sixth of the total body weight. Its functions include protection, sensation, and thermal regulation. Structurally, the skin is divided into a deep layer, the dermis, and a superficial layer, the epidermis. The epidermis is made up of five layers of cells in thick skin and four layers of cells in thin skin. From superficial to deep, thick skin consists of firstly, the stratum corneum on the surface, then the stratum lucidum, the stratum granulosum, the stratus spinosum and the stratum germinativum. In thin skin, however, the stratum lucidum, choice 2, is not present. So the correct answer to question is choice 2.

Front 217

Which of the following layers of the epidermis is least cytodifferentiated
1. Stratum basale
2. Stratum corneum
3. Stratum spinosum
4. Prickle-cell layer
5. Stratum granulosum

Back 217

The correct answer is choice 1. Let's review the layers of the epidermis. Stratum basale, choice 1, is the deepest layer and consists of a single layer of columnar cells. This layer and the stratum spinosum, choice 3, above it produce the replacement cells for all other epidermal layers. However, the stratum spinosum layer cells are more flat and more differentiated than. the stratum basale. Choice 5, stratum granulosum, is above the stratum spinosum and the cells in this layer contain keratohyalin and they are more flattened. Stratum corneum, choice 2, contains the dead, flattened keratinized surface cells which flake off to the outside. Choice 4, a prickle cell layer, refers to the stratum spinosum, choice 3, and describes the appearance of the cells in the stratum spinosum. So the correct answer to question is choice 1.

Front 218

Which of the following ligaments of the temporomandibular joint is attached to the circumference of the mandibular fossa, the articular tubercle, and to the neck of the condyle of the mandible?
A. Articular Capsule
B. Articular Disk
C. Lateral
D. Sphenomandibular
E. Stylomandibular

Back 218

The correct answer is A. The articular capsule (choice A) of the temporomandibular joint is attached to the circumference of the mandibular fossa and the articular tubercle, and to the neck of the condyle of the mandible. The articular disk (choice B) is located between the condyle of the mandible and mandibular fossa. The lateral ligament (choice C) is attached to the lateral surface of the zygomatic arch and to the tubercle on its inferior border superiorly. It is also connected to the lateral surface and posterior border of the neck of the mandible inferiorly. The sphenomandibular ligament (choice D) is attached to the spine of the sphenoid bone and to the lingula of the mandibular foramen. The stylomandibular ligament (choice E) extends from the apex of the styloid process of the temporal bone to the ramus of the mandible between the Masseter and Pterygoideus medialis (medial pterygoid).

Front 219

Which of the following may cause dead tracts in dentin?
1. Caries
2. Erosion
3. Cavity preparation
4. Odontoblastic crowding
5. Any of the above

Back 219

The correct answer is choice 5. Dark areas in dentinal tubules viewed under the light microscope are known as dead tracts. They are believed to be dead or coagulated cytoplasmic processes of odontoblasts or degenerated contents of the tubules. Common causes of dead tracts are any acute aggravations of the cytoplasmic processes of the odontoblasts. These would include caries, erosion and cavity preparation. Since the dead tracts are also found in unerupted and intact mature teeth, they have other nonpathological causes including crowding of the odontoblasts. So actually all four answers are correct, and the correct answer to question #1 is choice 5

Front 220

Which of the following muscles insert(s) onto the neck of the condyle?
A. Masseter
B. Temporalis
C. Lateral pterygoid
D. Medial pterygoid

Back 220

The correct answer is choice C. The lateral pterygoid inserts (in part) onto the fovea of the neck of the condyle. Choice A is incorrect. The masseter inserts along the lateral surface of the mandibular ramus. Choice B is incorrect. The temporalis inserts on the coronoid process of the mandible. Choice D is incorrect. The medial pterygoid inserts on the medial surface of the mandibular ramus, below the mandibular foramen.

Front 221

Which of the following muscles receives its motor supply from the facial nerve?
1. Masseter
2. Temporal
3. Buccinator
4. Lateral pterygoid
5. Tensor veli palatini

Back 221

he correct answer is choice 3. Let's review the choices. The masseter and temporalis (choices 1 and 2) are muscles of mastication and act primarily as closing or elevating muscles. They receive their innervation from cranial nerve 5; in particular, from motor efferents in the anterior division of the mandibular nerve or V3. Choice 4, the lateral pterygoid, is also a muscle of mastication and it generally depresses, opens or protrudes the mandible. It also receives innervation from the anterior division of the mandibular nerve. Choice 5, tensor veli palatini, tightens the soft palate and is also innervated by the anterior division of the mandibular nerve, in particular, by the branch to the medial pterygoid. This leaves the buccinator muscle which makes up the bulk of the cheek and is innervated by cranial nerve 7, the facial nerve; in particular, the buccal branches. So the correct answer to question is choice 3.

Front 222

Which of the following muscles serve to raise the soft palate during swallowing?
A. Levator veli palatini
B. Palatopharyngeus
C. Palatoglossus
D. Salpingopharyngeus
E. Tensor veli palatini

Back 222

The correct answer is A. Movement of the soft palate occurs in the following manner: The soft palate is raised by the contraction of the levator veli palatini (choice A). At the same time that the soft palate is being raised, the superior constrictor muscle contracts to pull the posterior pharyngeal wall forward. The palatopharyngeus muscle (choice B) also contracts to pull the palatopharyngeal arches medially. This results in the nasal part of the pharynx being closed off from the oral part. The palatoglossus muscle (choice C) pulls the root of the tongue upward and backward. The salpingopharyngeus (choice D) serves to elevate the larynx and pharynx during the act of swallowing. The tensor veli palatini (choice E) muscles move the soft palate downward.

Front 223

Which of the following muscles serves as the forearm's principal extensor?
1. Pronator teres
2. Brachioradialis
3. Triceps brachii
4. Coracobrachialis
5. Extensor carpi radialis longus

Back 223

The correct answer is choice 3. The principal extensor of the forearm is the triceps brachii, choice 3. Its main action is to extend the forearm because its direction of pull is posterior to the axis of the elbow joint. The pronator teres, choice 1, acts to pronate the hand and flex the forearm. Brachioradialis, choice 2, acts to initiate supination and pronation and to flex the forearm. Coracobrachialis, choice 4, acts primarily to flex the arm and abduct it. Extensor carpi radialis longus, choice 5, acts to extend and abduct the hand. So the correct answer to question is choice 3.

Front 224

Which of the following nerves contributes to the motor innervation of intrinsic muscles of the tongue?
A. V3
B. VII
C. IX
D. XII

Back 224

The correct answer is choice D. The hypoglossal nerve provides innervation to all intrinsic and extrinsic muscles of the tongue except palatoglossus. Choice A is incorrect. The motor division of V3 supplies the four muscles of mastication, the tensor tympani and tensor veli palatini, and mylohyoid and anterior belly of digastric, all of which are derived from the first pharyngeal arch. Choice B is incorrect. CN VII supplies muscles derived from the second pharyngeal arch. Muscles of the tongue originate from occipital somites. Choice C is incorrect. CN IX, the nerve of the third arch, supplies only stylopharyngeus. It conveys sensory information, general and special (taste) from the posterior one-third of the tongue.

Front 225

Which of the following nerves innervate the upper canine and incisor teeth?
A. Anterior superior alveolar nerve
B. Middle superior alveolar nerve
C. Posterior superior alveolar nerve
D. Tympanic nerve
E. Zygomatic nerve

Back 225

The correct answer is A. The maxillary nerve arises from the trigeminal ganglion located in the cranial fossa and branches into the anterior superior alveolar nerve, middle superior alveolar nerve, posterior superior alveolar nerve, and zygomatic nerve. It also has meningeal and ganglionic branches. The anterior superior alveolar nerve (choice A) innervates the upper canine and incisor teeth as well as the lateral wall and floor of the nose. The middle superior alveolar nerve (choice B) supplies the upper premolar teeth and the adjoining parts of the gum and cheek. The posterior superior alveolar nerve (choice C) supplies the maxillary sinus, upper molar teeth and the adjoining parts of the cheek and gingiva. There may be some overlap innervation of the maxillary teeth. The tympanic nerve (choice D) supplies the lining of the tympanic cavity and the zygomatic nerve (choice E) supplies the skin of the face.

Front 226

Which of the following nerves innervates the capsule of the temporomandibular joint?
1. Facial
2. Buccal
3. Maxillary
4. Mylohyoid
5. Auriculotemporal

Back 226

The correct answer is choice 5. The temporal mandibular joint is a synovial joint formed by the condyle of the mandible articulating against the mandibular or glenoid fossa of the temporal bone. The innervation of the temporal mandibular joint including the joint capsule is provided mainly from the auriculotemporal branch of the mandibular division of the trigeminal nerve which is cranial nerve V. So the correct answer to question is choice 5.

Front 227

Which of the following nerves innervates the trapezius muscle?
A. Radial
B. Axillary
C. Accessory
D. Thoracodorsal
E. Long thoracic

Back 227

The correct answer is choice C. The spinal accessory nerve (CN XI) originates from upper cervical spinal cord segments. A root is formed which ascends through foramen magnum to join the cranial portion of the nerve, which arises from the brainstem. The nerve exits the skull through the jugular foramen, and the spinal portion passes to the posterior triangle of the neck, where it supplies sternocleidomastoid and trapezius. Choice A is incorrect. The radial nerve arises from the posterior cord of the brachial plexus. It innervates extensor muscles of the arm and forearm. Choice B is incorrect. The axillary nerve is a terminal branch of the posterior cord of the brachial plexus. It supplies deltoid and teres minor. Choice D is incorrect. The thoracodorsal nerve is a branch of the posterior cord of the brachial plexus. Also known as the middle subscapular nerve, it supplies latissimus dorsi. Choice E is incorrect. The long thoracic nerve arises from the roots of the brachial plexus. It supplies serratus anterior.

Front 228

Which of the following nerves is the MOST likely to become injured in fractures of the mid-humeral shaft?
A. Ulnar
B. Radial
C. Median
D. Axillary
E. Musculocutaneous

Back 228

The correct answer is choice B. The radial nerve travels in the radial (spiral) groove on the posterior aspect of the midhumeral shaft. Choice A is incorrect. The ulnar nerve passes posterior to the medial epicondyle of the humerus at its most inferior aspect. Choice C is incorrect. The median nerve lies in the anterior compartment of the arm on the brachialis muscle. It is unlikely to be damaged by a midhumeral fracture. Choice D is incorrect. The axillary nerve passes from the axilla through the quadrangular space to reach deltoid and teres minor. It is subject to injury in fractures of the surgical neck of the humerus. Choice E is incorrect. The musculocutaneous nerve is never in direct contact with the humerus and is not likely to be injured in a humeral fracture.

Front 229

Which of the following papillae of the tongue are the largest, are the least numerous, have many taste buds, and are associated with the ducts of von Ebner's glands?
1. Foliate
2. Filiform
3. Fungiform
4. Circumvallate

Back 229

The correct answer is choice 4. The mucosa of the dorsal surface of the tongue has four different types of lingual papillae. Some of these have a mechanical function while others bear taste buds and have a sensory function. Choice 1, the foliate papillae, contain only a few taste buds and resemble sharp parallel clefts of varying lengths on the lateral tongue. Choice 2, the filiform papillae, cover the anterior portion of the tongue. These are cone shaped and contain no taste buds. Interspersed between the filiform papillae are the isolated fungiform papillae, choice 3. These are round and reddish and contain a few taste buds. Last, but not least, the circumvallate papillae, choice 4, are the largest type of lingual papillae. They are surrounded by a deep circular groove into which open the ducts of von Ebner's gland, which is a minor salivary gland. They are also the least numerous, usually consisting of 8-12 on the tongue, and they contain many tastebuds. So the correct answer to question is choice 4.

Front 230

Which of the following nerves innervate the upper canine and incisor teeth?
A. Anterior superior alveolar nerve
B. Middle superior alveolar nerve
C. Posterior superior alveolar nerve
D. Tympanic nerve
E. Zygomatic nerve

Back 230

The correct answer is A. The maxillary nerve arises from the trigeminal ganglion located in the cranial fossa and branches into the anterior superior alveolar nerve, middle superior alveolar nerve, posterior superior alveolar nerve, and zygomatic nerve. It also has meningeal and ganglionic branches. The anterior superior alveolar nerve (choice A) innervates the upper canine and incisor teeth as well as the lateral wall and floor of the nose. The middle superior alveolar nerve (choice B) supplies the upper premolar teeth and the adjoining parts of the gum and cheek. The posterior superior alveolar nerve (choice C) supplies the maxillary sinus, upper molar teeth and the adjoining parts of the cheek and gingiva. There may be some overlap innervation of the maxillary teeth. The tympanic nerve (choice D) supplies the lining of the tympanic cavity and the zygomatic nerve (choice E) supplies the skin of the face.

Front 231

Which of the following represent fan-shaped, hypocalcified areas that originate at the dentinoenamel junction and extend into enamel for part of its thickness?
A. Tufts
B. Spindles
C. Lamellae
D. Hunter-Schreger bands
E. Contour lines of Owen

Back 231

The correct answer is choice A. Tufts are hypocalcified enamel rods and less mineralized interprismatic organic substance extending from the DEJ into enamel. Enamel spindles are short dentinal tubules extending into enamel and ending blindly. Enamel lamellae are hypocalcified areas of enamel extending from the outer surface inward towards the dentin. They form between enamel prisms. Hunter-Schreger bands are regular lines seen in enamel as a result of changes in orientation of the enamel prisms. Contour lines of Owen are found in dentin, not enamel, and represent disturbances in the mineralization of incremental layers of dentin. The correct answer to question is choice A.

Front 232

Which of the following nerves innervates the capsule of the temporomandibular joint?
1. Facial
2. Buccal
3. Maxillary
4. Mylohyoid
5. Auriculotemporal

Back 232

The correct answer is choice 5. The temporal mandibular joint is a synovial joint formed by the condyle of the mandible articulating against the mandibular or glenoid fossa of the temporal bone. The innervation of the temporal mandibular joint including the joint capsule is provided mainly from the auriculotemporal branch of the mandibular division of the trigeminal nerve which is cranial nerve V. So the correct answer to question is choice 5.

Front 233

Which of the following represents the cranial nerve that supplies derivatives of the third branchial arch?
A. Facial
B. Accessory
C. Trigeminal
D. Hypoglossal
E. Glossopharyngeal

Back 233

The correct answer is choice E. The glossopharyngeal nerve is the nerve of the third pharyngeal (branchial) arch. The only muscle derived from the third arch is stylopharyngeus. Choice A is incorrect. The facial nerve is the nerve of the second arch. Choice B is incorrect. The spinal accessory innervates trapezius and sternocleidomastoid, neither of which originates from pharyngeal arches. Choice C is incorrect. CN V3 is the nerve of the first arch. Choice D is incorrect. The hypoglossal nerve is a somatic nerve which innervates muscles of the tongue.

Front 234

Which of the following nerves innervates the trapezius muscle?
A. Radial
B. Axillary
C. Accessory
D. Thoracodorsal
E. Long thoracic

Back 234

The correct answer is choice C. The spinal accessory nerve (CN XI) originates from upper cervical spinal cord segments. A root is formed which ascends through foramen magnum to join the cranial portion of the nerve, which arises from the brainstem. The nerve exits the skull through the jugular foramen, and the spinal portion passes to the posterior triangle of the neck, where it supplies sternocleidomastoid and trapezius. Choice A is incorrect. The radial nerve arises from the posterior cord of the brachial plexus. It innervates extensor muscles of the arm and forearm. Choice B is incorrect. The axillary nerve is a terminal branch of the posterior cord of the brachial plexus. It supplies deltoid and teres minor. Choice D is incorrect. The thoracodorsal nerve is a branch of the posterior cord of the brachial plexus. Also known as the middle subscapular nerve, it supplies latissimus dorsi. Choice E is incorrect. The long thoracic nerve arises from the roots of the brachial plexus. It supplies serratus anterior.

Front 235

Which of the following represents the location of the cell bodies of pain fibers in the glossopharyngeal nerve?
A. Otic ganglion
B. Nucleus ambiguus
C. Trigeminal (semilunar) ganglion
D. Spinal nucleus of cranial nerve V
E. Superior ganglion of cranial nerve IX

Back 235

The correct answer is choice E. Sensory cell bodies for fibers in CN IX are found in the superior or inferior ganglia of the nerve. Choice A is incorrect. The otic ganglion consists of postsynaptic cell bodies of parasympathetic fibers which supply the parotid gland. Choice B is incorrect. The nucleus ambiguus contains motor neurons for fibers of cranial nerves IX, X and XI. Choice C is incorrect. The trigeminal ganglion contains sensory cell bodies for nerve fibers of each of the divisions of CN V. Choice D is incorrect. The spinal nucleus of V contains secondary cell bodies in the pathway concerned with pain and other general sensation.

Front 236

Which of the following nerves is the MOST likely to become injured in fractures of the mid-humeral shaft?
A. Ulnar
B. Radial
C. Median
D. Axillary
E. Musculocutaneous

Back 236

The correct answer is choice B. The radial nerve travels in the radial (spiral) groove on the posterior aspect of the midhumeral shaft. Choice A is incorrect. The ulnar nerve passes posterior to the medial epicondyle of the humerus at its most inferior aspect. Choice C is incorrect. The median nerve lies in the anterior compartment of the arm on the brachialis muscle. It is unlikely to be damaged by a midhumeral fracture. Choice D is incorrect. The axillary nerve passes from the axilla through the quadrangular space to reach deltoid and teres minor. It is subject to injury in fractures of the surgical neck of the humerus. Choice E is incorrect. The musculocutaneous nerve is never in direct contact with the humerus and is not likely to be injured in a humeral fracture.

Front 237

Which of the following represents the main support of the wall of a bronchus?
A. Smooth muscle
B. Hyaline cartilage
C. Elastic membranes
D. Dense irregular connective tissue
E. Elastic and collagenous connective tissue

Back 237

The correct answer is choice B. Cartilaginous rings surround the primary bronchi. Choice A is incorrect. Smooth muscle is the major component in the walls of bronchioles. Choice C is incorrect. Elastic fibers are present in all parts of the bronchial tree, but do not represent the major component in any. Choice D is incorrect. Dense, irregular connective tissue is not the major component of the primary bronchus. Choice E is incorrect. Elastic and collagenous connective tissue are present in primary bronchi and their branches, but are not the major components.

Front 238

Which of the following papillae of the tongue are the largest, are the least numerous, have many taste buds, and are associated with the ducts of von Ebner's glands?
1. Foliate
2. Filiform
3. Fungiform
4. Circumvallate

Back 238

The correct answer is choice 4. The mucosa of the dorsal surface of the tongue has four different types of lingual papillae. Some of these have a mechanical function while others bear taste buds and have a sensory function. Choice 1, the foliate papillae, contain only a few taste buds and resemble sharp parallel clefts of varying lengths on the lateral tongue. Choice 2, the filiform papillae, cover the anterior portion of the tongue. These are cone shaped and contain no taste buds. Interspersed between the filiform papillae are the isolated fungiform papillae, choice 3. These are round and reddish and contain a few taste buds. Last, but not least, the circumvallate papillae, choice 4, are the largest type of lingual papillae. They are surrounded by a deep circular groove into which open the ducts of von Ebner's gland, which is a minor salivary gland. They are also the least numerous, usually consisting of 8-12 on the tongue, and they contain many tastebuds. So the correct answer to question is choice 4.

Front 239

Which of the following represents the organelle that is typically composed of vesicles and of curved, flattened cisternae that are parallel to one another?
1. Centriole
2. Mitochondrion
3. Golgi complex
4. Rough endoplasmic reticulum
5. Smooth endoplasmic reticulum

Back 239

The correct answer is choice 3. From the description given, the Golgi complex, choice 3, is the only possible response. The Golgi complex is primarily involved in the packaging of proteins and other secretory products into membrane-bound vesicles for exocytosis. Centrioles, choice 1, are structures involved in formation of the mitotic apparatus along which chromosomes migrate during mitosis. Their shape would resemble cylinders with microtubules inside. Mitochondria, choice 2, are elongated cigar-shaped organelles involved in ATP production. Rough endoplasmic reticulum, choice 4, consists of a network of tubules and flattened cisternae which are studded with ribosomes on the surface. Rough endoplasmic reticulum is mainly responsible for protein synthesis. Smooth endoplasmic reticulum. choice 5, consists of a network of tubules and vesicles. It plays an important role in lipid biosynthesis and it is thought to be part of the inuacellular transport system. So the correct answer to question is choice 3.

Front 240

Which of the following represent fan-shaped, hypocalcified areas that originate at the dentinoenamel junction and extend into enamel for part of its thickness?
A. Tufts
B. Spindles
C. Lamellae
D. Hunter-Schreger bands
E. Contour lines of Owen

Back 240

The correct answer is choice A. Tufts are hypocalcified enamel rods and less mineralized interprismatic organic substance extending from the DEJ into enamel. Enamel spindles are short dentinal tubules extending into enamel and ending blindly. Enamel lamellae are hypocalcified areas of enamel extending from the outer surface inward towards the dentin. They form between enamel prisms. Hunter-Schreger bands are regular lines seen in enamel as a result of changes in orientation of the enamel prisms. Contour lines of Owen are found in dentin, not enamel, and represent disturbances in the mineralization of incremental layers of dentin. The correct answer to question is choice A.

Front 241

Which of the following represents the cranial nerve that supplies derivatives of the third branchial arch?
A. Facial
B. Accessory
C. Trigeminal
D. Hypoglossal
E. Glossopharyngeal

Back 241

The correct answer is choice E. The glossopharyngeal nerve is the nerve of the third pharyngeal (branchial) arch. The only muscle derived from the third arch is stylopharyngeus. Choice A is incorrect. The facial nerve is the nerve of the second arch. Choice B is incorrect. The spinal accessory innervates trapezius and sternocleidomastoid, neither of which originates from pharyngeal arches. Choice C is incorrect. CN V3 is the nerve of the first arch. Choice D is incorrect. The hypoglossal nerve is a somatic nerve which innervates muscles of the tongue.

Front 242

Which of the following represents the location of the cell bodies of pain fibers in the glossopharyngeal nerve?
A. Otic ganglion
B. Nucleus ambiguus
C. Trigeminal (semilunar) ganglion
D. Spinal nucleus of cranial nerve V
E. Superior ganglion of cranial nerve IX

Back 242

The correct answer is choice E. Sensory cell bodies for fibers in CN IX are found in the superior or inferior ganglia of the nerve. Choice A is incorrect. The otic ganglion consists of postsynaptic cell bodies of parasympathetic fibers which supply the parotid gland. Choice B is incorrect. The nucleus ambiguus contains motor neurons for fibers of cranial nerves IX, X and XI. Choice C is incorrect. The trigeminal ganglion contains sensory cell bodies for nerve fibers of each of the divisions of CN V. Choice D is incorrect. The spinal nucleus of V contains secondary cell bodies in the pathway concerned with pain and other general sensation.

Front 243

Which of the following represents the main support of the wall of a bronchus?
A. Smooth muscle
B. Hyaline cartilage
C. Elastic membranes
D. Dense irregular connective tissue
E. Elastic and collagenous connective tissue

Back 243

The correct answer is choice B. Cartilaginous rings surround the primary bronchi. Choice A is incorrect. Smooth muscle is the major component in the walls of bronchioles. Choice C is incorrect. Elastic fibers are present in all parts of the bronchial tree, but do not represent the major component in any. Choice D is incorrect. Dense, irregular connective tissue is not the major component of the primary bronchus. Choice E is incorrect. Elastic and collagenous connective tissue are present in primary bronchi and their branches, but are not the major components.

Front 244

Which of the following represents the organelle that is typically composed of vesicles and of curved, flattened cisternae that are parallel to one another?
1. Centriole
2. Mitochondrion
3. Golgi complex
4. Rough endoplasmic reticulum
5. Smooth endoplasmic reticulum

Back 244

The correct answer is choice 3. From the description given, the Golgi complex, choice 3, is the only possible response. The Golgi complex is primarily involved in the packaging of proteins and other secretory products into membrane-bound vesicles for exocytosis. Centrioles, choice 1, are structures involved in formation of the mitotic apparatus along which chromosomes migrate during mitosis. Their shape would resemble cylinders with microtubules inside. Mitochondria, choice 2, are elongated cigar-shaped organelles involved in ATP production. Rough endoplasmic reticulum, choice 4, consists of a network of tubules and flattened cisternae which are studded with ribosomes on the surface. Rough endoplasmic reticulum is mainly responsible for protein synthesis. Smooth endoplasmic reticulum. choice 5, consists of a network of tubules and vesicles. It plays an important role in lipid biosynthesis and it is thought to be part of the inuacellular transport system. So the correct answer to question is choice 3.

Front 245

Which of the following represents the secretory product of the parafollicular cells of the thyroid gland?
A. Iodine
B. Protease
C. Thyroxine
D. Calcitonin
E. Thyroglobulin

Back 245

The correct answer is choice D.
The thyroid gland produces two types of hormones from two different cell types within the gland. Follicular cells are epithelial cells which produce thyroxin(T4 or tetraiodothyronine) and T3 (triiodothyronine). These hormones control basal metabolic rate. Parafollicular cells secrete calcitonin, the hormone which reduces plasma calcium levels. Choice A is incorrect. Dietary iodine is a mineral required by the follicular cells to produce T3 and T4. Choice B is incorrect. Protease refers to any protein-digesting enzyme. They are used in the thyroid to release T3 and T4 from their storage form. thyroglobulin(choice E). Choice C, thyroxine, as mentioned, is the hormone T4. So the correct answer to question 1 is choice D.

Front 246

Which of the following statements regarding the mechanics of inspiration are incorrect?
A. The diaphragm is the primary muscle involved in inspiration
B. The ribs are raised superiorly
C. The suprapleural membrane is fixed
D. The sternum is fixed
E. The tone of the muscles of the anterior abdominal wall is decreased

Back 246

The correct answer is D. Ventilation consists of two phases, inspiration and expiration. These phases occur by the alternate increase and decrease of the capacity of the thoracic cavity, respectively. During inspiration the capacity of the thoracic cavity increases. The process of inspiration is prompted by the diaphragm, which is the primary muscle involved in inspiration (choice A). During this phase the following events occur: The ribs are raised superiorly (choice B), the suprapleural membrane remains fixed (choice C) and the tone of the muscles of the anterior abdominal wall is decreased (choice E). Since the sternum moves anteriorly during inspiration and is not fixed, choice D is the correct answer.

Front 247

Which of the following strata of the epidermis is the LEAST cytodifferentiated?
A. Basale
B. Corneum
C. Spinosum
D. Granulosum

Back 247

he correct answer is choice A. In the stratum basale, undifferentiated epidermal cells specialize and begin their rise to the surface of the skin. This layer of cells is in contact with the dermis. and much mitotic activity is seen here. The cells are cuboidal in shape. As they rise to the next layer, the stratum spinosum(prickly cell layer), they become more flattened. Above that are three to five layers of cells of the stratum granulosum(granular layer). They are flattened and contain keratohyalin granules. Above this is the stratum lucidum (clear layer). These cells have lost their nuclei, and the layer appears clear. The outermost layer is stratum corneum, highly keratinized and composed of dead cells. These dead cells are constantly flaking off (desquamation). The correct answer to question is choice A.

Front 248

Which of the following structural changes is NOT encountered in passing along the respiratory system from the trachea to a respiratory bronchiole?
1. Decrease in goblet cells
2. Decrease in ciliated cells
3. Total loss of cartilage from the wall
4. Progressive change from stratified squamous to cuboidal epithelial lining

Back 248

The correct answer is choice 4. As air passes the trachea, it enters the two extrapulmonary bronchi which are outside the lung. Air then passes to the intrapulmonary bronchi, terminal bronchioles, respiratory bronchioles, and finally to alveoli. The terminal bronchioles and respiratory bronchioles lack goblet cells in their epithelium, so choice 1 is true and not the answer. The epithelial lining changes from pseudostratified columnar ciliated to thinner simpler columnar and eventually, in the terminal and respiratory bronchioles, to simple columnar or cuboidal ciliated epithelium without goblet cells. So choice 2 is true and not the answer. Choice 4 is false and is our answer. Choice 3 is also true and not our answer. Cartilage is present in the trachea, extrapulmonary and intrapulmonary bronchi, but absent in the terminal and respiratory bronchioles. So the correct answer to question is choice 4.

Front 249

Which of the following structures contacts posteriorly with the isthmus of the thyroid gland?
A. Larynx
B. Pharynx
C. Trachea
D. Esophagus
E. Carotid Sheath

Back 249

The correct answer is choice C. The isthmus of the thyroid gland rests against the upper tracheal rings. Choice A is incorrect. The larynx is superior to the thyroid gland. Choice B is incorrect. The lower portion of the pharynx (laryngopharynx) lies posterior and lateral to the larynx. Choice D is incorrect. The esophagus runs inferiorly from the larynx. It is located posterior to the trachea. Choice E is incorrect. The carotid sheath, which contains the internal jugular vein, common carotid artery, and vagus nerve, lies lateral to the visceral compartment of the neck, which contains larynx, pharynx, trachea, esophagus and thyroid gland.

Front 250

Which of the following structures contacts the thyroid gland?
1. Lingual nerve
2. Phrenic nerve
3. Thoracic duct
4. Thyroarytenoid muscle
5. Recurrent laryngeal nerve

Back 250

The correct answer is choice 5. The thyroid gland produces thyroxin and thyrocalcitonin which regulates metabolism and calcium balance, respectively. It consists of two lobes that are bound tightly to the trachea and larynx by the pretracheal layer of the deep cervical fascia. This fascia splits into two layers at the posterior border of each lobe and branches of the inferior thyroid artery and the recurrent laryngeal nerve lie between them. Therefore, branches of the inferior thyroid artery and the recurrent laryngeal nerve contact the thyroid gland directly. So the correct answer to question is choice 5.

Front 251

Which of the following structures is formed from the first branchial (visceral) arch?
1. Hyoid bone
2. Buccinator muscle
3. Stylopharyngeus muscle
4. Lateral pterygoid muscle
5. Superior parathyroid gland

Back 251

The correct answer is choice 4. The branchial arches form from proliferation of mesoderm in the lateral wall of the pharynx. Each arch gives rise to a cartilaginous bar, a muscle element, an artery and a nerve from the developing brain. Choice 1. the hyoid bone, is derived from the cartilaginous element of the second and third branchial arches. Choice 2, the buccinator, along with all muscles of facial expression, are derived from the second branchial arch. Choice 3, the stylopharyngeus muscle, is derived from the third branchial arch. Choice 4, the lateral pterygoid, and all muscles of mastication, are derived from the first branchial arch and this is, therefore, our correct answer. Choice 5, the superior parathyroid gland, is formed from the fourth pharyngeal pouch. Pharyngeal pouches lie in between the branchial arches. So the correct answer to question is choice 4.

Front 252

Which of the following structures may be found within the posterior mediastinum?
1. Heart
2. Phrenic nerve
3. Thoracic duct
4. Arch of the aorta
5. Recurrent laryngeal nerve

Back 252

The correct answer is choice 3. The posterior mediastinum refers to the section of the thorax behind the pericardial sac. It is bounded laterally by the mediastinal pleura and by the diaphragm below. Superiorly, it continues into the superior mediastinum. It runs from approximately vertebral level T4 to T12. It contains the descending aorta, the esophagus, the thoracic duct, the sympathetic trunk and the vagus nerve. The superior mediastinum, which is superior to the posterior mediastinum, contains the thymus gland and vascular structures to the heart, including the aortic arch (choice 4) and the brachiocephalic veins and arteries. Choice 1, the heart, is in the middle mediastinum, as is choice 2, the phrenic nerve. Choice 5, the recurrent laryngeal nerve, is considered to be in the superior mediastinum with the thymus gland. So the correct answer to question is choice 3.

Front 253

Which of the following two muscles attach to the pterygomandibular raphe?
A. Buccinator and palatopharyngeus
B. Medial pterygoid and palatopharyngeus
C. levator veli palatini and palatopharyngeus
D. Buccinator and superior pharyngeal constrictor

Back 253

The correct answer is choice D. The buccinator arises from the anterior aspect of the pterygomandibular raphe, which extends from the pterygoid hamulus to the posterior end of the mandible. The superior constrictor originates from the posterior aspect of the raphe. Choice A is incorrect. Palatopharyngeus originates from the hard and soft palate and inserts into the thyroid lamina and inferior pharyngeal wall. It forms the muscular core of the palatopharyngeal fold (posterior pillar of the fauces). Choice B is incorrect. The majority of fibers of medial pterygoid arise from the medial surface of the lateral pterygoid plate. Some fibers originate from the pyramidal process of the palatine bone and the tuberosity of the maxilla. It inserts on the medial surface of the ramus of the mandible, inferior to the mandibular foramen. Choice C is incorrect. Levator palati arises from the cartilage of the auditory (Eustachian) tube and inserts into the palatal aponeurosis.

Front 254

Which of the following types of epithelium is well adapted for secretory or absorptive functions?
A. Simple columnar
B. Simple squamous
C. Stratified cuboidal
D. Stratified squamous
E. Psuedostratified columnar

Back 254

The correct answer is choice A. Simple columnar epithelial cells are tall and single layered, and are found lining the digestive system from the stomach through the anus. Therefore, they are involved in both absorption and secretion, as the digestive lining both secretes enzymes and absorbs digested food and water. Simple squamous epithelial cells are single layered and flattened (thin). They are found in areas where a narrow distance between two areas is desirable, such as the lining of areas of the Bowman's capsule, and the endothelium of blood vessels. Simple cuboidal epithelium is cubelike and single layered, and is often found lining the ducts of glands. Stratified cuboidal is not generally found. Stratified squamous epithelium is multi-layered flat cells, and lines the oral cavity and esophagus. These two areas are not major absorptive or secretory sections. Pseudostratified columnar epithelium appears to be multilayered, but is not. Non-ciliated versions are found in parotid ducts and other glands, while ciliated types line the bronchi and bronchioles. So the correct answer to question is choice A.

Front 255

Which of the following types of tissues can be demonstrated on the posterior slope of the articular eminence?
A. Hyaline cartilage
B. Fibrocartilage
C. Fibrous connective tissue
D. Articular cartilage
E. Elastic cartilage

Back 255

The correct answer is choice C. Although the temperomandibular joint shares many characteristics with other joints, it also is distinct in many ways. While most articular surfaces in joints are covered by hyaline cartilage, the surfaces in the TMJ are covered by fibrous connective tissue. In addition, the condyle and bone of the articular eminence do not make direct contact, but rather, are separated by the fibrous disc of the TMJ. In older people, the fibrous connective tissue may develop small areas containg cartilage, and therefore become more like fibrocartilage. Note that elastic cartilage is found in areas such as the outer ear and epiglottis, where flexibility is needed. The correct answer to question is choice C.

Front 256

Which of the lymphoid tissues in the body are considered subepithelial and nonencapsulated?
1. Thymus gland and lymph nodes
2. Lymph nodes and aggregated nodules
3. Pharyngeal tonsils and thymus gland
4. Peyel's patches and pharyngeal tonsils

Back 256

The correct answer is choice 4. Peyer's patches are clusters of aggregated lymph follicles located within the mucosa of the small intestine. The pharyngeal tonsils are located on the posterior wall of the nasopharynx. Both the Peyer's patches and pharyngeal tonsils are not enclosed in a capsule and are subepithelial. Choice 1 is incorrect. The thymus gland is encapsulated by a dense fibrous capsule and contains an epithelial framework inside the gland. Lymph nodes are also encapsulated, so choice 2 is also incorrect. Aggregated lymph nodules are another name for Peyer's patches. Choice 3 is incorrect because, as noted, the thymus gland is encapsulated. It should be noted that Peyer's patches are believed to be involved in producing precursors of intestinal plasma cells which produce IgA. So the correct answer to question is choice 4.

Front 257

Which region of dentin is the most highly mineralized?
1. The peritubular
2. The intertubular
3. The interglobular

Back 257

The correct answer is choice 1. Dentin forms the bulk of the tooth. It is permeated by tubules which run from thc pulpal surface toward the amelodentinal and cementodentinal junctions. Between the tubules lie the bulk of the dentin known as intertubular dentin. Peritubular dentin, choice 1, is more highly mineralized than intertubular dentin, choice 2. The interglobular dentin, choice 3, refers to unmineralized or hypomineralized regions that remain between the mineralized dentin. These are chiefly found in the crown near the dentinoenamel junction. So the correct answer to question is choice 1.

Front 258

White matter of the spinal cord consists chiefly of which of the following?
A. Perineurium
B. Myelinated axons
C. Unmyelinated axons
D. Nerve cell bodies
E. Loose connective tissue

Back 258

The correct answer is choice B. Myelinated nerve fibers appear white in unfixed, fresh tissue as well as in standard fixed and stained preparations. Choice A is incorrect. The perineurium refers to the thin layer of connective tissue that invests nerve fibers; it is not grossly visible. Choice C is incorrect. Unmyelinated axons do not have the shiny, white appearance caused by the presence of the lipid-rich myelin. Choice D is incorrect. Nerve cell bodies comprise most of what is visible as grey matter in unstained sections of spinal cord and brain. Choice E is incorrect. Loose connective tissue is not present in abundance in the central nervous system.