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70 Cards in this Set
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A 38-year-old man has had thyroid surgery to remove his papillary carcinoma. The external laryngeal nerve that accompanies
the superior thyroid artery is damaged during the surgery. This injury could result in a severe impairment of function of which of the following? (A) Relax the vocal cords (B) Rotate the arytenoid cartilages (C) Tense the vocal cords (D) Widen the rima glottidis (E) Abduct the vocal cords |
C. The external laryngeal nerve innervates the cricothyroid muscle (major tensor), which tenses the vocal cord. The anterior part of the vocalis muscle can tense the vocal cord, and its posterior part can relax the vocal cord. The lateral cricoarytenoid muscle rotates the vocal process of the arytenoids cartilage medially, closing the rima glottides. The rima glottidis is
opened (widened) by rotating the vocal process of the arytenoids cartilage laterally by the poste- rior cricoarytenoid muscle. Other laryngeal muscles adduct the vocal cords. |
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27-year-old woman with a goiter comes to the hospital for surgical treatment. The surgeon must ligate the superior laryngeal artery
before surgically resecting the goiter, so care must be taken to avoid injury to which of the following nerves? (A) External laryngeal nerve (B) Internal laryngeal nerve (C) Superior laryngeal nerve (D) Hypoglossal nerve (E) Vagus nerve |
B. The internal laryngeal nerve accompanies the superior laryngeal artery, whereas the external laryngeal nerve accompanies the superior thyroid artery. The superior laryngeal, hypoglossal, and vagus nerves are not closely associated with the superior laryngeal artery.
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A 19-year-old woman complains of numb-
ness of the nasopharynx after surgical removal of the adenoid. A lesion of which of the fol- lowing nerves would be expected? (A) Maxillary nerve (B) Superior cervical ganglion (C) External laryngeal nerve (D) Glossopharyngeal nerve (E) Vagus nerve |
D. The glossopharyngeal nerve supplies sensory innervation to the mucosa of
the upper pharynx, whereas the vagus nerve supplies sensory innervation to the lower pharynx and larynx. The maxillary nerve supplies sensory innervation to the face below the level of the eye and above the level of the upper lip and the palate and nasal mucosa. The superior cervical ganglion contributes to a formation of the pharyngeal plexus but contains no afferent fibers. The external laryngeal nerve innervates the cricothyroid and inferior pharyngeal constrictor muscles. |
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During surgery on a 56-year-old man for a squamous cell carcinoma of the neck, a surgeon notices profuse bleeding from the deep
cervical artery. Which of the following arteries must be ligated immediately to stop bleeding? (A) Inferior thyroid artery (B) Transverse cervical artery (C) Thyrocervical trunk (D) Costocervical trunk (E) Ascending cervical artery |
D. The surgeon should ligate the costocervical trunk because it divides into the deep cervical and superior intercostal arteries. The thyrocervical trunk gives off the suprascapular, transverse cervical, and inferior thyroid artery. The ascending cervical artery is a branch of the inferior thyroid artery.
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A 17-year-old boy receives an injury of the phrenic nerve by a knife wound in the neck. The damaged nerve passes by which of the fol-
lowing structures in the neck? (A) Anterior to the subclavian vein (B) Posterior to the subclavian artery (C) Deep to the brachial plexus (D) Medial to the common carotid artery (E) Superficial to the anterior scalene muscle |
E. The phrenic nerve descends on the superficial surface of the anterior scalene muscle and passes into the thorax posterior to the subclavian vein, anterior to the subclavian ar-
tery, and lateral to the common carotid artery. The brachial plexus passes deep to the anterior sca- lene muscle. |
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A 45-year-old woman is suffering from numbness over the tip of her nose. Which of the following nerves is most likely to be damaged?
(A) Ophthalmic division of the trigeminal nerve (B) Maxillary division of the trigeminal nerve (C) Mandibular division of the trigeminal nerve (D) Facial nerve (E) Auriculotemporal nerve |
A. the skin over the tip of the nose is innervated by external nasal branch of the nasociliary branch of the ophthalmic division of the trigeminal nerve. The maxillary division of
the trigeminal nerve innervates the skin of the face above the upper lip but below the lower eyelid. The mandibular division of the trigeminal nerve supplies the lower part of the face below the lower lip. The facial nerve provides no cutaneous sensation on the face but innervates muscles of facial expression. The auriculotemporal nerve is a branch of the mandibular division of the trigeminal nerve arid innervates the skin of the auricle and the scalp. |
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A 26-year-old singer visits her physician— an ear, nose, and throat (ENT) surgeon—and complains of changes in her voice. A laryngo-
scopic examination demonstrates a lesion of the superior laryngeal nerve, causing weakness of which of the following muscles? (A) Inferior pharyngeal constrictor (B) Middle pharyngeal constrictor (C) Superior pharyngeal constrictor (D) Thyroarytenoid (E) Thyrohyoid |
A. The external laryngeal branch of the superior laryngeal nerve supplies the cricothyroid and inferior pharyngeal constrictor muscles. The superior, middle, and inferior pha-
ryngeal constrictors are innervated by the vagus nerve through the pharyngeal plexus. The re- current (or inferior) laryngeal nerve supplies the thyroarytenoid muscle, and the Cl via the hypoglossal nerve supplies the thyrohyoid muscle. |
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A 44-year-old man with "crocodile tears syndrome" has spontaneous lacrimation during eating because of misdirection of regenerating autonomic nerve fibers. Which of the following nerves has been injured?
(A) Facial nerve proximal to the geniculate ganglion (B) Auriculotemporal nerve (C) Chorda tympani in the infratemporal fossa (D) Facial nerve at the stylomastoid foramen (E) Lacrimal nerve |
A. "Crocodile tears syndrome" (lacrimation during eating) is caused by a lesion of the facial nerve proximal to the geniculate ganglion resulting from misdirection of regenerating parasympathetic fibers, which formerly innervated the salivary glands, to the lacrimal glands. An injury to the auriculotemporal nerve may result in Frey's syndrome (sweating while eating) resulting from misdirection of regenerating parasympathetic and sympathetic fibers. Chorda tym-
pani carries preganglionic parasympathetic fibers to the submandibular ganglion and taste fibers to the anterior two thirds of the tongue. The facial nerve innervates the muscles of facial expres- sion. The terminal part of the lacrimal nerve contains postganglionic parasympathetic fibers for lacrimation. |
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A young girl complains of dryness of the nose and the palate. This would indicate a lesion of which of the following ganglia?
(A) Nodose ganglion (B) Otic ganglion (C) Pterygopalatine ganglion (D) Submandibular ganglion (E) Ciliary ganglion |
C. Postganglionic parasympathetic fibers originating in the pterygopalatine ganglion innervate glands in the palate and nasal mucosa. The postganglionic parasympathetic fibers from the otic ganglion supply the parotid gland, those from the submandibular ganglion supply the submandibular and sublingual glands, and those from the ciliary ganglion supply the
ciliary muscle and sphincter pupillae. The nodose (inferior) ganglion of the vagus nerve is a sensory ganglion. |
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A 33-year-old woman develops Bell's palsy. She must be cautious because this can result in
corneal inflammation and subsequent ulceration. This symptom results from which of the following conditions? (A) Sensory loss of the cornea and conjunctiva (B) Lack of secretion of the parotid gland (C) Absence of the corneal blink reflex (D) Absence of sweating on the face (E) Inability to constrict the pupil |
C. Bell's palsy (facial paralysis) can involve inflammation of the cornea leading to corneal ulceration, which probably is attributable to an absence of the corneal blink re-
flex. This is due to paralysis of the orbicularis oculi, which closes the eyelid. Sensory loss of the cornea and conjunctiva is due to injury of the ophthalmic nerve. Lack of secretion of the parotid salivary gland is due to injury of the glossopharyngeal, tympanic, or lesser petrosal nerve. Absence of sweating is due to damage of the sympathetic nerve. Inability to constrict the pupil is due to paralysis of the sphincter pupillae or damage of parasympathetic nerve fibers to the sphincter. |
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A 39-year-old woman presents to your clinic with complaints of headache and dizziness. She has an infection of a cranial dural si-
nus; one that lies in the margin of the tentonum cerebelli and runs from the posterior end of the cavernous sinus to the transverse sinus is infected. Which of the following sinuses is affected by inflammation? (A) Straight sinuses (B) Inferior sagittal sinus (C) Sphenoparietal sinus (D) Superior petrosal sinuses (E) Cavernous sinus |
D. The superior petrosal sinus runs from the cavernous sinus to the transverse sinus along the attached margin of the tentorium cerebelli. This patient has meningitis (inflam-
mation of the meninges), which causes headache and dizziness. The straight sinus runs along the line of attachment of the falx cerebri to the tentorium cerebelli; the inferior sagittal sinus lies in the free edge of the falx cerebri; the sphenoparietal sinus lies along the posterior edge of the lesser wing of the sphenoid bone; the cavernous sinus lies on each side of the sella turcica and the body of the sphenoid bone. |
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A 34-year-old man in a bar fight suffers a knife wound that severs the abducens nerve proximal to its entrance into the orbit. Which
of the following conditions results from this injury? (A) Ptosis of the upper eyelid (B) Loss of the ability to dilate the pupil (C) External strabismus (lateral deviation) (D) Loss of visual accommodation (E) Internal strabismus (medial deviation) 17. A 67-year-old woman comes to her physi- cian complaining of visual loss. Her magnetic resonance imaging (MRI) scan shows an en- larged pituitary gland that lies in the sella tur- cica, immediately posterior and superior to which of the following structures? (A) Frontal sinus (B) Maxillary sinus |
E. The abducens nerve (CN VI) innervates the lateral rectus muscle, which abducts the eyeball. A lesion of the abducens nerve results in medial strabismus (medial devia-
tion) and diplopia (double vision). Ptosis of the upper eyelid is caused by lesions of the oculomotor nerve or sympathetic nerve to the levator palpebrae superioris. Inability to dilate the pupil is caused by a lesion of the sympathetic nerve to the dilator pupillae. The external strabismus (lateral deviation) is caused by paralysis of the medial rectus muscle, which is innervated by the oculomotor nerve. Loss of visual accommodation is due to a lesion of parasympathetic nerve fibers to the ciliary muscle. |
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A 24-year-old man falls from his motorcycle and lands in a creek. Death may result from bilateral severance of which of the following
nerves? (A) Trigeminal nerve (B) Facial nerve (C) Vagus nerve (D) Spinal accessory nerve (E) Hypoglossal nerve |
C. Bilateral severance of the vagus nerve (CN X) causes a loss of reflex control of circulation because of an increase in heart rate and blood pressure; poor digestion results
because of decreased gastrointestinal (GI) motility and secretion; and difficulty in swallowing, speaking, and breathing occurs because of paralysis of laryngeal and pharyngeal muscles. All of these effects may result in death. Bilateral severance of other nerves do not cause death. |
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A 25-year-old man is involved in an automobile accident and slams his head into a concrete wall of a bridge. His computed tomog-
raphy (CT) scan reveals that the middle meningeal artery has ruptured but the meninges remain intact. Blood leaking from this artery enters which of the following spaces? (A) Subarachnoid space (B) Subdural space (C) Epidural space (D) Subpial space (E) Cranial dural sinuses |
C. Rupture of the middle meningeal artery in the cranial cavity causes an
epidural hemorrhage. Subarachnoid hemorrhage is due to rupture of cerebral arteries and veins. Subdural hematoma is due to rupture of bridging cerebral veins as they pass from the brain surface into one of the venous sinuses. Subpial hemorrhage is due to damage to the small vessels of the pia and brain tissue. Cranial dural sinuses normally contain venous blood. |
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A 27-year-old paratrooper lands on a pine tree. Consequently, preganglionic parasympathetic nerves leaving the central nervous system are lacerated. Which of the following structures contain cell bodies of the damaged nerve fibers?
(A) Cervical and sacral spinal cord (B) Cervical and thoracic spinal cord (C) Brainstem and cervical spinal cord (-D) Thoracic and lumbar spinal cord (E) Brainstem and sacral spinal cord |
E. Preganglionic neurons of the parasympathetic nervous system are located in the brainstem (cranial outflow) and sacral spinal cord segments S2–S4 (sacral outflow). Pre-ganglionic sympathetic neurons are located in the thoracic and lumbar spinal cord.
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Following radical resection of a primary tongue tumor, a 72-year-old patient has lost general sensation on the anterior two thirds of the tongue. This is probably due to injury to
branches of which of the following nerves? (A) Trigeminal nerve (B) Facial nerve (C) Glossopharyngeal nerve (D) Vagus nerve (E) Hypoglossal nerve |
A. The anterior two thirds of the tongue are innervated by the lingual nerve, a branch of the mandibular division of the trigeminal nerve (CN V). The posterior one third of
the tongue is innervated by the glossopharyngeal nerve (CN IX) for general and taste sensations. The facial nerve supplies taste fiber to the tongue through the chorda tympani but does not supply general sensation. The vagus nerve supplies general sensation and taste sensation to the epiglottis by way of the internal laryngeal branch. The hypoglossal nerve innervates the tongue muscles. |
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A 67-year-old woman comes to her physician complaining of visual loss. Her magnetic resonance imaging (MRI) scan shows an enlarged pituitary gland that lies in the sella turcica, immediately posterior and superior to which of the following structures?
(A) Frontal sinus (B) Maxillary sinus (C) Ethmoid air cells (D) Mastoid air cells (E) Sphenoid sinus |
E. The pituitary gland lies in the hypophyseal fossa of the sella turcica of the sphenoid hone, which lies immediately posterior and superior to the sphenoid sinus and medial to the cavernous sinus. The frontal sinus lies in the frontal bone; the maxillary sinus lies in the
maxilla lateral to the lateral wall of the nasal cavity; the ethmoid sinus (composed of air cells) lies between the orbit and the nasal cavity; the mastoid air cells lie in the mastoid process of the temporal bone. |
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After having a tonsillectomy, a 57-year-old man with a long history of chewing tobacco use is unable to detect taste on the posterior
one third of his tongue. Which of the following nerves most likely has been injured? (A) Internal laryngeal nerve (B) Lingual nerve (C) Glossopharyngeal nerve (D) Greater palatine nerve (E) Chorda tympani |
C. The posterior one third of the tongue receives both general and taste innervation from the lingual branch of the glossopharyngeal nerve, The internal laryngeal nerve
supplies general and taste sensations to the epiglottis. The lingual nerve supplies general sensation to the anterior two thirds of the tongue. The greater palatine nerve innervates the hard palate and the inner surface of the maxillary gingival. The chorda tympani supplies taste sensation to anterior two thirds of the tongue and preganglionic parasympathetic fibers to the submandibular ganglion for supplying the submandibular and sublingual glands. |
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A 14-year-old boy hits his head on the asphalt road after falling off his skateboard. His radiograph reveals damage to the sella turcica.
This is probably due to fracture of which of the following bones? (A) Frontal bone (B) Ethmoid bone (C) Temporal hone (D) Basioccipital bone (E) Sphenoid bone |
E. The sella turcica is part of the sphenoid bone and lies superior to the sphenoid sinus. Therefore, none of the other bones listed are fractured,
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The nerve accompanying the superior thyroid artery may be damaged during an operation
on the thyroid gland. Which of the following functional defects may result from this injury? (A) Loss of sensation above the vocal cord (B) Loss of lateral rotation of the arytenoid cartilages (C) Paralysis of vocalis muscle (D) Lack of abduction of the vocal cord (E) Decreased tension of the vocal cord |
The superior thyroid artery is accompanied by the external laryngeal nerve, which innervates the cricothyroid muscle. Paralysis of this muscle due to a lesion of the external laryngeal nerve decreases tension of the vocal cord. Loss of sensation above the vocal cord is due to injury of the internal laryngeal nerve. The posterior crycoarytenoid muscle draws the muscular process of the arytenoid cartilage posteriorly and thereby rotates its vocal process laterally. Paralysis of the vocalis muscle is due to a lesion of the recurrent laryngeal nerve. Lack of abduction of the vocal cord results from paralysis of the posterior cricoarytenoid muscle.
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A 37-year-old patient has an infectious inflammation of the dural venous sinus closest to the pituitary gland and a secondary thrombus
formation. Which of the following is the most likely site of infection? (A) Straight sinus (B) Cavernous sinus (C) Superior petrosal sinus (D) Sigmoid sinus (E) Confluence of sinuses |
B. The dural venous sinus nearest the pituitary gland is the cavernous sinus. Cavernous sinus thrombophlebitis is an infectious inflammation of the sinus that may produce meningitis, papilledema, exophthalmos, and ophthalmoplegia. The other sinuses listed are not closely associated with the pituitary gland.
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A 53-year-old woman is diagnosed as having a pituitary tumor. If the tumor is large enough, she could exhibit which of the following disorders?
(A) Blindness (B) Bitemporal (heteronymous) hemianopia (C) Right nasal hemianopia (D) Left homonymous hemianopia (E) Binasal hemianopia |
B. Lesion of the optic chiasma by a pituitary tumor results in bitemporal hemianopia resulting from loss in the nasal field of vision of both eyes. Lesion of the optic nerve causes
blindness. The right perichiasmal lesion by an aneurysm of the internal carotid artery leads to right nasal hemianopia because of loss of vision in the nasal field of the right eye. Lesion of the right optic tract or optic radiation causes left homonymous hemianopia resulting from loss of the left half of the visual fields of both eyes. Aneurysms of both internal carotid arteries cause right and left perichiasrnal lesions, leading to binasal hemianopia (loss of vision in the nasal fields of both eyes). |
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A young singer at the local music theater visits her physician and complains of vocal difficulties. On examination, she is unable to abduct
the vocal cords during quiet breathing. Which of the following muscles is most likely paralyzed? (A) Vocalis muscle (B) Cricothyroid muscle (C) Oblique arytenoid muscle (D) Posterior cricoarytenoid muscle (E) Thyroarytenoid muscle |
D. The posterior cricoarytenoid muscle is the only muscle that abducts the vo-
cal cords during quiet breathing. All other laryngeal muscles adduct the vocal cords. |
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A 71-year-old woman often visits an emergency department with swallowing difficulties and subsequent choking while eating food. Which of the following pairs of muscles is most instrumental in preventing food from entering
the larynx and trachea during swallowing? (A) Sternohyoid and sternothyroid muscles (B) Oblique arytenoid and aryepiglottic muscles (C) Inferior pharyngeal constrictor and thyro- hyoid muscles (D) Levator veli palatini and tensor veli pala- tini muscles (E) Musculus uvulae and geniohyoid muscles |
B. The oblique arytenoid and aryepiglottic muscles tilt the arytenoid cartilages and approximate them, assisting in closing off the larynx and preventing food from entering the larynx and trachea during the process of swallowing. The cricopharyngeus fibers of the inferior pharyngeal constrictors act as a sphincter that prevents air from entering the esophagus. Other muscles are not involved in closing or opening the airway.
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A 31-year-old woman complains of
headache and dizziness after hitting a kitchen cabinet door with her head. Her magnetic resonance imaging (MRT) scan and venogram show a large blood clot in the great cerebral vein of Galen. The obstructed vein of the brain is a direct tributary of which of the following venous structures? (A) Emissary veins (B) Pterygoid venous plexus (C) Diploic veins (D) Dural venous sinuses (E) Internal jugular vein |
D. The veins of the brain are direct tributaries of the dural venous sinuses. The emissary veins connect the dural venous sinuses with the veins of the scalp; the pterygoid venous plexus communicates with the cavernous sinus through an emissary vein; the diploic veins lie in channels in the diploe of the skull and communicate with the dural sinuses, the veins of the scalp, and the meningeal veins.
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A 41-year-old woman overdoses on some prescription medications that have a common side effect of autonomic nerve stimulation.
Which of the following conditions or actions results from stimulation of the parasympathetic fibers to the eyeball? (A) Enhanced vision for distant objects (B) Dilation of the pupil (C) Contraction of capillaries in the iris (D) Contraction of the ciliary muscle (E) Flattening of the lens |
D. When the parasympathetic fibers to the eyeball are stimulated, the pupil constricts and the ciliary muscle contracts, resulting in a thicker lens and enhanced vision for
near objects (accommodation). Dilation of the pupil, contraction of capillaries in the iris, and enhanced ability to see distant objects (flattening of the lens) result from stimulation of sympathetic nerves. |
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A 53-year-old woman with a severe middle ear infection comes to a hospital. On examination, a physician finds the infection has in-
jured the tympanic nerve. The damaged nerve (A) Is a branch of the facial nerve (B) Contains postganglionic parasympathetic fibers (C) Synapses with fibers in the lesser petrosal nerve (D) Is a branch of the glossopharyngeal nerve (E) Forms the tympanic plexus in the exter- nal auditory meatus |
D. The tympanic nerve, or Jacobson's nerve, is a branch of the glossopharyngeal nerve, contains preganglionic parasympathetic fibers, and forms a tympanic plexus on the medial wall of the middle ear with sympathetic fibers. The tympanic nerve continues beyond the plexus as the lesser petrosal nerve, which transmits preganglionic parasympathetic fibers to the
otic ganglion for synapse. |
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A 13-year-old boy competing in a motocross competition falls from his bicycle and sustains massive head injuries. Which of the following cavities are separated from the mid-
dle cranial fossa by a thin layer of bone? (A) Auditory tube and bony orbit (B) Middle ear cavity and sphenoid sinus (C) Sigmoid sinus and frontal sinus (D) Sphenoid sinus and ethmoid sinus (E) Maxillary sinus and middle ear cavity |
B. The middle ear cavity is separated from the middle cranial fossa by the tegmen tympani, a thin plate of the petrous part of the temporal bone. A part of the roof of the sphenoid bone forms the floor of the hypophyseal fossa. The other pairs of sinuses or bony cavities are not separated from the middle cranial cavity.
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A 32-year-old house painter suffers from a head injury after falling off a ladder and bleeding in his head. During intraoperative testing, the
neurosurgeon notes loss of general sensation in the dura of the middle cranial fossa. Which of the following nerves has been affected? (A) Vagus nerve (B) Facial nerve (C) Hypoglossal nerve (D) Trigeminal nerve (E) Glossopharyngeal nerve |
D. The cranial dura in the middle cranial fossa is innervated by the maxillary and mandibular divisions of the trigeminal nerve, the dura in the anterior cranial fossa is inner-
vated by the ophthalmic division of the trigeminal nerve, and the dura in the posterior cranial fossa is innervated by the vagus and hypoglossal (C1 through the hypoglossal) nerves. The facial and glossopharyngeal nerves do not supply the cranial dura. |
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During a carotid endarterectomy of a 57- year-old man who suffered a stroke, the carotid sinus is damaged. A third-year medical student
in surgical rotation notices that the injured structure: (A) Is located at the origin of the external carotid artery (B) Is innervated by the facial nerve (C) Functions as a chemoreceptor (D) Is stimulated by changes in blood pressure (E) Communicates freely with the cavernous sinus |
D. The carotid sinus, a spindle-shaped dilatation of the origin of the internal carotid artery, is a pressoreceptor that is stimulated by changes in blood pressure. The carotid sinus is at the origin of the internal carotid artery, innervated by the carotid sinus branch of the
glossopharyngeal nerve and nerve to the carotid body of the vagus nerve. It is not a venous sinus and thus does not communicate with the cavernous sinus. The carotid body functions as a chemoreceptor. |
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During a game, a 26-year-old baseball player is hit in the head by a baseball that fractures the optic canal. Which of the following
pairs of structures is most likely to be damaged? (A) Optic nerve and ophthalmic vein (B) Ophthalmic vein and ophthalmic nerve (C) Ophthalmic artery and optic nerve (D) Ophthalmic nerve and optic nerve (E) Ophthalmic artery and ophthalmic vein |
C. The optic canal transmits the optic nerve and ophthalmic artery. The oph-
thalmic nerve and ophthalmic vein enter the orbit through the superior orbital fissure. |
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A 43-year-old man has new-onset of difficulty with speaking. Examination by the ear, nose, and throat (ENT) resident reveals problems in elevating the hyoid bone and floor of
the mouth, secondary to paralysis of the posterior belly of the digastric muscle. Which of the following nerves would most likely be involved? (A) Accessory nerve (B) Trigeminal nerve (C) Ansa cervicalis (D) Facial nerve (E) Glossopharyngeal nerve |
D. The digastric posterior belly is innervated by the facial nerve, whereas the digastric anterior belly is innervated by the trigeminal nerve. The accessory nerve supplies the sternocleidomastoid and trapezius muscles. The ansa cervicalis innervates the infrahyoid (or strap) muscles. The glossopharyngeal nerve supplies the stylopharyngeus muscle.
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The drummer of a local band presents to your clinic with hearing loss. Otoscopic examination reveals loss of contraction of the tensor
tympani and the stapedius, which prevents damage to the eardrum and middle ear ossicles. These muscles are most likely controlled by which of the following nerves? (A) Chorda tympani and tympanic nerve (B) Trigeminal and facial nerves (C) Auditory and vagus nerves (D) Facial and auditory nerves (E) Trigeminal and accessory nerves |
B. The tensor tympani is innervated by the trigeminal nerve, and the stapedius
is innervated by the facial nerve. The other nerves are not involved. |
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The pupil in the eye of a 43-year-old patient remains small even when room lighting is dim. Which of the following nerves would be injured?
(A) Trochlear nerve (B) Superior cervical ganglion (C) Oculomotor nerve (D) Ophthalmic nerve (E) Abducens nerve |
B. The superior cervical ganglion is damaged. When the pupil remains small in a dimly lit room, it is an indication that postganglionic sympathetic fibers that originate from the superior cervical ganglion and innervate the dilator pupillae (radial muscles of the iris) are
damaged. Other nerves contain no sympathetic fibers but the oculomotor nerve contains pre- ganglionic parasympathetic fibers. |
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A pharyngeal (gag) reflex is the contraction of the pharyngeal constrictor muscles elicited
by touching the back of a patient's pharynx (e.g., with a tongue depressor). Afferent nerve fibers that innervated the pharyngeal mucosa are branches of which of the following nerves? (A) Trigeminal nerve (B) Facial nerve (C) Glossopharyngeal nerve (D) Vagus nerve (E) Hypoglossal nerve |
C. The afferent limb of the pharyngeal (gag) reflex is a pharyngeal branch of the glossopharyngeal nerve, whereas the vagus nerve mediates the efferent limb. The trigeminal,
facial, and hypoglossal nerves are not involved in the gag reflex. |
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A patient can move his eyeballs normally and see distant objects clearly but cannot focus on near objects. This condition may indicate
damage to which of the following structures? (A) Ciliary ganglion and oculomotor nerve (B) Oculomotor nerve and long ciliary nerve (C) Short ciliary nerves and ciliary ganglion (D) Superior cervical ganglion and long ciliary nerve (E) Oculomotor, trochlear, and abducens nerves |
C. Damage to the parasympathetic ciliary ganglion and parasympathetic fibers in the short ciliary nerve impairs the ability to focus on close objects (accommodation). Because
the patient can move his eyeballs normally, the oculomotor nerve is not damaged even if this nerve contains preganglionic parasympathetic fibers. The patient is able to see distant objects clearly because the long ciliary nerve also carries sympathetic fibers to the dilator pupillae. The ability to move the eyeball normally indicates that the oculomotor, trochlear, and abducens nerves are intact. |
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A benign tumor in the orbit of 49-year-old man compresses a structure that runs through
both the superior orbital fissure and the common tendinous ring. Which of the following structures is most likely damaged? (A) Frontal nerve (B) Lacrimal nerve (C) Trochlear nerve (D) Abducens nerve (E) Ophthalmic vein |
D. The abducens nerve enters the orbit through the superior orbital fissure and the common tendinous ring. The trochlear, lacrimal, and frontal nerves and the ophthalmic vein enter the orbit through the superior orbital fissure outside the common tendinous ring.
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A 37-year-old man feels a little discomfort when moving his tongue, pharynx, and larynx. Physical examination indicates that the
muscles attached to the styloid process are paralyzed. Which of the following groups of cranial nerves are damaged? (A) Facial, glossopharyngeal, and hypoglossal nerves (B) Hypoglossal, vagus, and facial nerves (C) Glossopharyngeal, trigeminal, and vagus nerves (D) Vagus, spinal accessory, and hypoglossal nerves (E) Facial, glossopharyngeal, and vagus |
A. The styloid process provides attachments for the stylohyoid, styloglossus, and stylopharyngeus muscles. The stylohyoid muscle is innervated by the facial nerve, the styloglossus muscle by the hypoglossal nerve, and the stylopharyngeus muscle by the glossopharyngeal nerve. No other muscles are attached to the styloid process.
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A 32-year-old woman has hoarseness in her voice, and her uvula is deviated to the left
on phonation. Which of the following nerves is damaged? (A) Right trigeminal nerve (B) Left trigeminal nerve (C) Right vagus nerve (D) Left vagus nerve (E) Left glossopharyngeal nerve |
C. The vagus nerve innervates the museums uvulae. A lesion of the vagus nerve causes deviation of the uvula toward the opposite side of the injury. Because her uvula deviates to
the left on phonation, the right vagus nerve is damaged. Hoarseness is caused by a paralysis of the laryngeal muscles resulting from damage to skeletal motor fibers in the recurrent laryngeal branch of the vagus nerve. |
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A high school basketball player experiences a sudden difficulty in breathing and is brought to an emergency room. When a low
tracheotomy is performed below the isthmus of the thyroid, which of the following vessels may be encountered? (A) Inferior thyroid artery (B) Inferior thyroid vein (C) Costocervical trunk (D) Superior thyroid artery (E) Right brachiocephalic vein |
B. A low tracheotomy is a surgical incision of the trachea through the neck, below the isthmus of the thyroid gland. The inferior thyroid veins drain the thyroid gland, descend in front of the trachea, and enter the brachiocephalic veins. Consequently, these veins are closely associated with the isthmus of the thyroid gland. Other blood vessels are not closely related with
the front of the trachea and the isthmus of the thyroid gland. |
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A 59-year-old man complains of numbness in the anterior cervical triangle. Damage has therefore occurred to which of the following
nerves? (A) Phrenic nerve (B) Greater auricular nerve (C) Transverse cervical nerve (D) Supraclavicular nerve (E) Lesser occipital nerve |
C. The transverse cervical nerve turns around the posterior border of the sternocleidomastoid and innervates the skin of the anterior cervical triangle. The phrenic nerve, a branch of the cervical plexus, contains motor and sensory fibers but no cutaneous nerve fibers. The
greater auricular nerve innervates the skin behind the auricle and on the parotid gland. The supra- clavicular nerve innervates the skin over the clavicle and the shoulder. The lesser occipital nerve in- nervates the scalp behind the auricle. |
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A 53-year-old man has difficulty with
breathing through his nose. On examination, his physician finds that he has swelling of the mucous membranes of the superior nasal mea- tus. Which opening of the paranasal sinuses is most likely plugged? (A) Middle ethmoidal sinus (B) Maxillary sinus (C) Posterior ethmoidal sinus (D) Anterior ethmoidal sinus (E) Frontal sinus |
C. The posterior ethmoidal sinus opens into the superior nasal meatus. The maxillary, frontal, and anterior and middle cthmoidal sinuses drain into the middle nasal meatus.
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Following a penetrated injury in the submandibular triangle, the tongue of a 45-year-old patient deviates to the left on protrusion. Which of the following nerves is injured?
(A) Right lingual nerve (B) Left lingual nerve (C) Right hypoglossal nerve (D) Left hypoglossal nerve (E) Left glossopharyngeal nerve |
D. A lesion of the hypoglossal nerve causes deviation of the tongue toward the injured side on protrusion. The lingual and glossopharyngeal nerves do not supply the tongue muscles.
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A 47-year-old man cannot move his eye laterally. Which of the following conditions would cause this type of inability to move the eye?
(A) Tumor of the pituitary gland (B) Occlusion of the posterior cerebral artery (C) Infection in the maxillary sinus (D) Infection in the cavernous sinus (E) Tumor in the anterior cranial fossa |
D. The abducens nerve, which innervates the lateral rectus muscle, runs through the middle of the cavernous sinus. The other conditions listed do not injure the abducens nerve. A tumor in the pituitary gland may injure the optic chiasma, causing bitemporal hemianopsia.
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A young boy with a tooth abscess from a
long-standing infection suffers damage of the lingual nerve as it enters the oral cavity. Which of the following structures contain cell bodies of injured nerve fibers? (A) Geniculate and otic ganglia (B) Trigeminal and submandibular ganglia (C) Trigeminal and dorsal root ganglia (D) Geniculate and trigeminal ganglia (E) Geniculate and pterygopalatine ganglia |
D. The lingual nerve is joined by the chorda tympani in the infratemporal fossa. Therefore, the lingual nerve contains general somatic afferent (GSA) fibers whose cell bodies are located in the trigeminal ganglion and special somatic afferent (SSA) or taste fibers that have cell bod-
ies located in the geniculate ganglion. In addition, the lingual nerve carries parasympathetic pre- ganglionic general visceral efferent (GVE) fibers that originated from the chorda tympani; the cell bodies are located in the superior salivatory nucleus in the pons. The chorda tympani and lingual nerves contain no fibers from the otic, submandibular, pterygopalatine, or dorsal root ganglia. |
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A 61-year-old woman is found to have ocular lymphoma invading her optic canal. Which of the following structures would most likely be damaged?
(A) Ophthalmic vein (B) Ophthalmic nerve (C) Oculomotor nerve (D) Trochlear nerve (E) Ophthalmic artery |
E. The optic canal transmits the ophthalmic artery and optic nerve. The ophthalmic nerve, ophthalmic vein, and oculomotor and trochlear nerves enter the orbit through the
superior orbital fissure. |
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A 76-year-old man with swallowing difficulties undergoes imaging for a possible mass. The computed tomography (CT) scan image at
the level of the cricothyroid ligament in his neck should show which of the following structures? (A) Inferior laryngeal nerves (B) External carotid arteries (C) Inferior thyroid veins (D) Thyrocervical trunks (E) Internal laryngeal nerves |
A. A computed tomography (CT) scan through the cricothyroid ligament shows the inferior laryngeal nerves, which are the terminal portion of the recurrent laryngeal nerves above the lower border of the cricoid cartilage. The external carotid arteries and the internal lar-
yngeal nerves lie above the cricothyroid ligament, and the inferior thyroid veins and the thyro- cervical trunks lie below the ligament. |
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A knife wound has severed the oculomotor nerve in a 45-year-old man. Which of the following conditions would occur because of this injury?
(A) Constricted pupil (B) Abduction of the eyeball (C) Complete ptosis (D) Impaired lacrimal secretion (E) Paralysis of the ciliary muscle |
E. The oculomotor nerve carries parasympathetic fibers to the ciliary and sphincter pupillae ciliary muscles; thus, its lesion leads to ciliary muscle paralysis and a dilated
pupil. The abducens nerve supplies the lateral rectus, which is an abductor of the eye. The levator palpebrae superioris inserts on the tarsal plate in the upper eyelid, which is innervated by sympa- thetic fibers. Thus, a lesion of the oculomotor nerve does not cause complete ptosis. The secreto- motor fibers for lacrimal secretion come through the pterygopalatine ganglion. Thus, severance of the oculomotor nerve has no effect on lacrimal secretion. |
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The muscles that are of branchiomeric origin are paralyzed in a 26-year-old patient. A lesion of which of the following nerves would
cause muscle dysfunction? (A) Oculomotor nerves (B) Trochlear nerves (C) Trigeminal nerves (D) Abducens nerves (E) Hypoglossal nerves |
C. Special visceral efferent (SVE) nerve fibers originate from the first branchial arch (trigeminal), the second arch (facial), the third arch (glossopharyngeal), and the fourth and sixth arches (vagus). Nerves that supply the muscles of the eyeball (oculomotor, trochlear, ab-
ducens) and tongue (hypoglossal) are not of branchiomeric origin. |
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During surgery for a malignant parotid tumor in a 69-year-old woman, the main trunk of the facial nerve is lacerated. Which of the fol-
lowing muscles is paralyzed? (A) Masseter muscle (B) Stylopharyngeus muscle (C) Anterior belly of the digastric muscle (D) Buccinator muscle (E) Tensor tympani |
D. The buccinator muscle is innervated by the facial nerve. The masseter, anterior belly of the digastric, and tensor tympani muscles are innervated by the mandibular division of the trigeminal nerve. The stylopharyngeus muscle is innervated by the glossopharyngeal nerve.
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During a gang-fight, a 17-year-old boy is punched and his nasal septum is broken. Which of the following structures would be
damaged? (A) Septal cartilage and nasal bone (B) Inferior concha and vomer (C) Vomer and perpendicular plate of ethmoid (D) Septal cartilage and middle concha (E) Cribriform plate and frontal bone |
C. The nasal septum is formed primarily by the vomer, the perpendicular plate of ethmoid bone, and the septal cartilage. The superior, middle, and inferior conchae form the lateral wall of the nasal cavity. The ethmoid (cribriform plate), nasal, frontal, and sphenoid (body) bones form the roof. The floor is formed by the palatine process of the maxilla and the horizontal
plate of the palatine bone. |
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A 58-year-old woman comes to a hospital and complains of progressive loss of voice,
numbness, loss of taste on the back part of her tongue, and difficulty in shrugging her shoulders. Her magnetic resonance imaging (MRI) scan reveals a dural meningioma that compresses nerves leaving the skull. These nerves leave the skull through which of the following openings? (A) Foramen spinosum (B) Foramen rotundum (C) Internal auditory meatus (D) Jugular foramen (E) Foramen lacerum |
D. A loss of voice is due to an injury to the recurrent laryngeal nerve of the vagus nerve; numbness and loss of taste on the posterior part of the tongue is due to a lesion of the
glossopharyngeal nerve; an inability to shrug the shoulder is due to damage of the accessory nerve. These three cranial nerves exit the skull through the jugular foramen. The foramen spinosum transmits the middle meningeal artery. The foramen rotundum transmits the maxillary division of the trigeminal nerve. The internal auditory meatus transmits the facial and vestibulocochlear nerves. The foramen lacerum transmits nothing, but its upper part is traversed by the internal carotid artery with sympathetic nerve plexus. |
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A 21-year old woman presents to her physician with a swelling on her neck. On examination, she is diagnosed with an infection
within the carotid sheath. Which of the following structures would be damaged? (A) Vagus nerve and middle cervical ganglion (B) Internal carotid artery and recurrent laryngeal nerve (C) Internal jugular vein and vagus nerve (D) Sympathetic trunk and common carotid artery (E) External carotid artery and ansa cervicalis |
C. The carotid sheath contains the internal jugular vein, vagus nerve, and common and internal carotid arteries. The recurrent laryngeal nerve lies in a groove between the trachea and esophagus. The sympathetic trunk, with superior and middle cervical ganglia, lies behind
the carotid sheath. The external carotid artery is not contained within the carotid sheath. The ansa cervicalis lies superficial to or within the carotid sheath. |
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An angiogram of a 45-year-old man shows an occlusion of the costocervical trunk. This obstruction could produce a marked decrease
in the blood flow in which of the following arteries? (A) Superior thoracic artery (B) fransverse cervical artery (C) Ascending cervical artery (D) Deep cervical artery (E) Inferior thyroid artery |
D. The costocervical trunk gives rise to the deep cervical and superior intercostal arteries. The superior thoracic artery arises from the axillary artery. The transverse cervical, inferior thyroid, and suprascapular arteries arise from the thyrocervical trunk. The ascending cervical artery arises from the inferior thyroid artery.
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A 20-year-old guard at the gate of the Royal King's palace blinks his eyes when a strong wind hits the cornea of his eye. The afferent fibers of the corneal reflex arc are carried
by which of the following nerves? (A) Optic nerve (B) Long ciliary nerve (C) Nasociliary nerve (D) Zygomatic nerve (E) Oculomotor nerve |
C. The afferent limb of the corneal reflex arc is the nasociliary nerve, and its efferent limb is the facial nerve. The other nerves are not involved in the reflex arc. The opening of the eye is carried by the oculomotor nerve, but it is not a part of the corneal reflex.
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A 57-year-old man comes to a local hospital with fever, headache, nausea, and vomiting. Laboratory tests reveal an infection and radio-
logic examination localizes the infection to the cavernous sinus. Which of the following nerves would be unaffected by this condition? (A) Oculomotor nerves (B) Abducens nerves (C) Trochlear nerves (D) Mandibular nerves (E) Ophthalmic nerves |
D. The mandibular division of the trigeminal nerve does not lie in the wall of the cavernous sinus, whereas the oculomotor, abducens, trochlear, and ophthalmic nerves do.
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A 7-year-old girl has difficulty breathing through her nose and is brought to her pediatrician. On examination, she is diagnosed with
adenoids. Which of the following tonsils is enlarged? (A) Palatine tonsil (B) Pharyngeal tonsil (C) Tubal tonsil (D) Lingual tonsil (E) Eustachian tonsil |
B. The enlarged pharyngeal tonsil is called the adenoid, which obstructs passage of air from the nasal cavities through the choanae into the nasopharynx, thus causing diffi-
culty in nasal breathing and phonation. The tubal tonsil is also called the eustachian tonsil. The palatine tonsil is called the faucial tonsil. The submerged tonsil is a palatine tonsil that is shrunken and atrophied and is partly or entirely hidden by the palatoglossal arch. |
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A 59-year-old woman with pain at the side of her skull comes to the emergency department. An emergent head computed tomogra-
phy (CT) scan shows a large lesion in the internal auditory meatus. This condition may progress and damage which of the following pairs of structures? (A) Vagus and glossopharyngeal nerves (B) Internal carotid and vertebral arteries (C) Internal jugular vein and trigeminal nerve (D) Facial and vestibulocochlear nerves (E) Hypoglossal and accessory nerves |
D. The internal auditory meatus transmits the facial and vestibulocochlear nerves. The jugular foramen transmits the glossopharyngeal, vagus, and accessory nerves and the
internal jugular vein. The ophthalmic, maxillary, and mandibular divisions of the trigeminal nerve run through the superior orbital fissure, foramen rotundum, and foramen ovale, respectively. The hypoglossal nerve runs through the hypoglossal canal. |
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After ingesting a toxic substance found in her friend's home, a 12-year-old girl is unable to close her lips. Which of the following mus-
cles may be paralyzed? (A) Levator labii superioris (B) Zygomaticus minor (C) Orbicularis oris (D) Lateral pterygoid (E) Depressor labii inferioris |
C. The lips are closed by the orbicularis oris muscles. The lips are opened by the levator labii superioris, zygomaticus minor, and depressor labii inferioris muscles. The lateral pterygoid muscle can open the mouth by depressing the lower jaw.
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A 37-year-old man receives a direct blow to his head and is brought to an emergency department. His x-ray film shows a fracture of the
floor of the middle cranial cavity, causing severance of the greater petrosal nerve. Which of the following conditions could be produced by this injury? (A) Increased lacrimal gland secretion (B) Loss of taste sensation in the epiglottis (C) Dryness in the nose and palate (D) Decreased parotid gland secretion (E) Loss of sensation in the pharynx |
C. The greater petrosal nerve carries parasympathetic (preganglionic) fibers, which are secretomotor fibers to the lacrimal glands and mucous glands in the nasal cavity and palate; carries taste fibers from the palate; and carries general visceral afferent (GVA) fibers from the nasal cavity, palate, and roof of the oral cavity but not from the pharynx and larynx. There-
fore, a lesion of the greater petrosal nerve causes dryness in the nose and palate and decreased lacrimal secretion. A decreased parotid gland secretion is due to a lesion of the lesser petrosal nerve. Taste sensation in the epiglottis is carried by the internal laryngeal branch of the superior laryngeal nerve. General visceral sensation in the pharynx is carried by the glossopharyngeal nerve. |
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A 71-year-old man suffers from a known benign tumor in the pterygoid canal. Which of the following nerve fibers could be injured by this condition?
(A) Postganglionic parasympathetic fibers (B) Taste fibers from the epiglottis (C) General somatic afferent (GSA) fibers (D) l'reganglionic sympathetic fibers (E) General visceral afferent (GVA) fibers |
E. The nerve of the pterygoid canal (vidian nerve) contains taste (special visceral afferent [SVA]) fibers from the palate, general visceral afferent (GVA) fibers, postganglionic
sympathetic fibers, and preganglionic parasympathetic fibers. |
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A 65-year-old man with multiple vision problems comes to a local eye clinic. The pupillary light reflex can be eliminated by cutting
which of the following nerves? (A) Short ciliary, ophthalmic, and oculomotor nerves (B) Long ciliary, optic, and short ciliary nerves (C) Oculomotor, short ciliary, and optic nerves (D) Optic and long ciliary nerves; ciliary ganglion (E) Ophthalmic and optic nerves; ciliary ganglion |
C. The efferent limbs of the reflex are involved in the pupillary light reflex (i.e., constriction of the pupil in response to illumination of the retina) are composed of parasympa-
thetic preganglionic fibers in the oculomotor nerve, parasympathetic fibers and ganglionic cells in the ciliary ganglion, and parasympathetic postganglionic fibers in the short ciliary nerves. The afferent limbs of this reflex are optic nerve fibers. The long ciliary nerves contain postganglionic sympathetic fibers. The ophthalmic nerve contains general somatic afferent (GSA) fibers. |
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A 22-year-old patient has dryness of the corneal surface of his eye because of a lack of tears. Which of the following nerves may be
damaged? (A) Proximal portion of the lacrimal nerve (B) Zygomatic branch of the facial nerve (C) Lesser petrosal nerve (D) Greater petrosal nerve (E) Deep petrosal nerve |
D. The secretomotor fibers to the lacrimal gland are parasympathetic fibers that run in the facial, greater petrosal, vidian (nerve of the pterygoid canal), maxillary, zygomatic (of maxillary), zygomaticotemporal, and lacrimal (terminal portion) nerves. The lesser petrosal nerve carries secretomotor (preganglionic parasympathetic) fibers to the parotid gland. The deep
petrosal nerve contains postganglionic sympathetic fibers. The zygomatic branch of the facial nerve supplies the facial muscles. |
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A 12-year-old boy has difficulty in breathing because he is choking on food. A school nurse performs the Valsalva's maneuver to expel air from his lungs and thus dislodge the
food. When that fails, she performs a needle cricothyrotomy, which would open into which of the following regions? (A) Rima glottidis (B) Laryngeal vestibule (C) Laryngeal ventricle (D) Infraglottic cavity (E) Piriform recess |
D. The infraglottic cavity extends from the rima glottidis to the lower border of the cricoid cartilage. The rima glottidis is the space between the vocal folds and arytenoid car-
tilages. The vestibule extends from the laryngeal inlet to the vestibular folds. The ventricle extends between the vestibular fold and the vocal fold. The piriform recess is a pear-shaped fossa in the wall of the laryngopharynx lateral to the arytenoid cartilage. |
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A 59 year-old stroke patient is unable to swallow because of a nerve injury. Which of the following nerves is unaffected?
(A) Hypoglossal nerve (B) Spinal accessory nerve (C) Vagus nerve (D) Facial nerve (E) Trigeminal nerve |
B. The spinal accessory nerve supplies the sternocleidomastoid and trapezius muscles, which are not involved in the act of swallowing. Swallowing involves movements of the tongue to push the food into the oropharynx, elevation of the soft palate to close the entrance
of the nasopharynx, elevation of the hyoid bone and the larynx to close the opening into the larynx, and contraction of the pharyngeal constrictors to move the food through the pharynx. The hypoglossal nerve supplies all of the tongue muscles except the palatoglossus, which is innervated by the vagus nerve. The vagus nerve innervates the muscles of the palate, larynx, and pharynx. The mandibular division of the trigeminal nerve supplies the suprahyoid muscles (e.g., the anterior belly of the digastric and the mylohyoid muscles). |
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A 64-year-old woman is unable to open her mouth or jaw because of tetanus resulting from a penetrating wound from a rusty nail. Which of the following muscles would most
likely he paralyzed? (A) Masseter muscle (B) Medial pterygoid muscle (C) Lateral pterygoid muscle (D) Buccinator muscle (E) Temporalis muscle |
C. The lateral pterygoid muscle opens the mouth by depressing the jaw. The masseter, medial pterygoid, and temporalis muscles close the jaw. The buccinator muscle is a muscle of facial expression.
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67. A 60-year-old man is unable to open his eye because of a rare neuromuscular disease. Which of the following muscles would most
likely be paralyzed? (A) Orbicularis oculi (B) Orbicularis oris (C) Frontalis (D) Levator palpebrae superioris (E) Superior rectus |
D. The levator palpebrae superioris muscle opens the eye by elevating the upper eyelid. The orbicularis oculi closes the eye, the orbicularis oris closes the lips, the frontalis el-
evates the eyebrow, and the superior rectus elevates the eyeball. |
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A 31-year-old hockey player is hit in the head by a puck. His radiogram shows a fracture of the foramen rotundum. Which of the following nerves would be damaged by this event?
(A) Ophthalmic nerve (B) Mandibular nerve (C) Maxillary nerve (D) Optic nerve (E) Trochlear nerve |
C. The maxillary nerve runs through the foramen rotundum; the ophthalmic nerve runs through the supraorbital fissure; the mandibular nerve passes through the foramen
ovale; the optic nerve runs through the optic canal; the trochlear nerve passes through the superior orbital fissure. |
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46-year-old man visits the speech therapist complaining of dryness of the mouth. The therapist performs a swallowing study and, on
examination, finds that the man has a lack of salivary secretion from the submandibular gland. This indicates a lesion of which of the following nervous structures? (A) Lingual nerve at its origin (B) Chorda tympani in the middle ear cavity (C) Superior cervical ganglion (D) Lesser petrosal nerve (E) Auriculotemporal nerve |
B. The chorda tympani nerve contains preganglionic parasympathetic fibers responsible for secretion of the submandibular gland. The lingual nerve at its origin is not yet joined by the chorda tympani. The superior cervical ganglion provides sympathetic fibers, which supply blood vessels in the submandibular gland. The lesser petrosal nerve contains preganglionic parasympathetic fibers that synapse in the otic ganglion. The auriculotemporal nerve contains postganglionic parasympathetic fibers, which are responsible for secretion of the parotid gland.
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A 51-year-old woman traveling through British Columbia can see the beautiful blue sky with white clouds but is unable to focus on her
face in the mirror. Her lack of accommodation results from paralysis of which of the following muscles? (A) Tarsal muscle (B) Sphincter pupillae (C) Dilator pupillae (D) Ciliary muscles (E) Orbitalis muscles |
D. Accommodation occurs with contraction of the ciliary muscles and is mediated by parasympathetic fibers running within the oculomotor nerve. The levator palpebrae su-
perioris inserts on the tarsal smooth muscle plate in the upper eyelid and skin of the upper eyelid and opens the eye by elevating the upper eyelid. The sphincter pupillae and dilator pupillae constrict and dilate the pupil, respectively. The orbitalis muscle is smooth muscle that bridges the inferior orbital fissure and protrudes the eye. |
