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423 Cards in this Set

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What are the contents of the cranial cavity?
cranial meninges (dura, arachnoid and pia matter), dural reflections (parts of dura that subdivides the portions of the brain)., dural venous sinus (for drainage of brain), cranial fossae (spaces where various parts of the brain sit), cranial nerves, and blood supply to the brain
What are cranial meninges and what function do they serve?
coverings of the brain that lie immediately internal to the cranium, they protect the brain, form the supporting framework for arteries, veins and venous sinuses, and enclose a fluid-filled cavity (subarachnoid space)
What are the three components of the cranial meninges?
1. dura mater: tough, thick external fibrous layer
2. arachnoid matter: thin intermediate layer
3. pia mater: delicate internal vasculated layer
What is the leptomenix?
combination of the arachnoid and pia, separated from each other by the subarachnoid (leptomeningeal) space which contains CSF
What is the purpose of CSF?
maintains the balance of extracellular fluid in the brain, similar to blood in constitution, provides nutrients but has less protein and a different ion concentration, if CSF is gone then the arachnoid collapses against the brain
Where is CSF made and what is its course?
made by the choroid plexus of the four ventricles of the brain, leaves the ventricular system and enters the subarachnoid space between the arachnoid and pia, where it cushions and nourishes the brain
Describe the dura matter of meninge.
AKA pachymenix, tightly adhered to the interior of the skull, no epidural space deep to it, changes when reaches the foramen magnum where is an epidural space, forms the periosteum of the skull
What are the layers of the dura?
consists of the periosteal (external, formed by the periosteum covering the internal surface of the calvaria) and meningeal layer (internal, fibrous membrane), meningeal arteries travel within the space between the two layers of the dura
Describe the periosteal layer of the dura.
attaches tenaciously with the cranium, along the suture lines and in the cranial base, continuous at the cranial foramina with the periosteum on the external surface of the calvaria, not continuous with the spinal cord because that dura only consists of meningeal layer
Describe the meningeal layer of the dura.
tightly adherent to the periosteal layer except at dural sinuses and infoldings (dural reflections)
What is an epidural hematoma?
can occur following skull fractures that tear the underlying meningeal arteries (middle), bleeds between the external periosteal layer and the calvaria, high pressure bleed that takes up a lot of space (a space occupying lesion like a tumor), can push the brain out through the foramen magnum, can occur following skull fractures that tear the underlying meningeal arteries
What are some of the effects caused by an epidural hematoma?
very serious, can lead to uncal herniation (uncus being pushed against CN III), positive Babinski sign (due to compression of cortex blocking transmission, toes don’t curl (no flexor-plantar reflex), if in right foot then in the left brain (pyramid crosses at very bottom of brain stem)), mydriasis (dilated pupil due to loss of parasympathetics from CN III due to uncal herniation) and ptosis (droopy eyelid, lose the ability to open eyelid, from CN III)
What are the dural infoldings and what purpose do they serve?
divide the cranial cavity into compartments, forming partial partitions (dural septa) between certain parts of the brain and provide support for other parts, include the cerebral falx, cerebellar tentorium, cerebellar falx, and sellar diaphragm
Describe the cerebral falx (falx cerebri), its location and boundaries.
the largest of the dural infoldings, lies in the longitudinal cerebral fissue that separates the right and left cerebral hemispheres, attaches in the median plane to the internal surface of the calvaria, from the frontal crest of the frontal bone and crista galli of the ethmoid bone anteriorly to the internal occipital protuberance posteriorly, it ends by becoming continuous with the cerebellar tentorium
Describe the cerebellar tentorium (tentorium cerebelli), its location and boundaries.
the 2nd largest dural infolding, a wide crescentic septum that separates the occipital lobes of the cerebral hemispheres from the cerebellum, attaches rostrally to the clinoid processes of the sphenoid, rostrolaterally to the petrous part of the temporal bone and posterolaterally to the internal surface of the occipital bone and part of the parietal bone, divides the cranial cavity cavity into supratentorial and infratentorial compartments, has a concave anteromedial border that produces the tentorial notch
what is the purpose of the tentorial notch?
allows for the exit of the brainstem from the posterior into the middle cranial fossa
Describe the cerebellar falx, its location and boundaries.
a vertical dural infolding that lies inferior to the cerebellar tenotrium in the posterior part of the posterior cranial fossa, it is attached to the internal occipital crest and partially separates the cerebellar hemispheres
Describe the sellar diaphragm, its location and boundaries.
the smallest dural infolding, is a circular sheet of dura that is suspended between the clinoid processes forming a partial roof over the hypophysial fossa in the sphenoid, the sellar diaphragm covers the pituitary gland in the fossa and has an aperture for passage of the infundibulum and hypophysial veins
What are the dural venous sinuses, where do they form and what they drain?
are endothelium-lined spaces between the periosteal and the meningeal layers of the dura, form where the dural septa attach along the free edge of the falx cerebri and in relation to formations of the cranial floor, large veins from the surface of the brain empty into these sinuses and most of the blood from the brain ultimately drains through them into the IJVs
Describe the superior sagittal sinus, its location and boundaries and what veins it receives.
lies in the convex attached forder of the cerebral falx, begins at crista galli and ends near the internal occipital protuberance at the confluence of sinuses, receives the superior cerebral veins and communicates on each side through slit-like openings with the lateral venous lacunae (lateral expansions of the superior sagittal sinus)
What sinuses meet at the confluence of sinuses?
superior sagittal, straight, occipital and transverse sinuses
What are arachnoid granulations and what purpose do they serve?
they are a collection of arachnoid villi, protrude through the meningeal layer into the dural venous sinuses and effect transfer of CSF to the venous system (gaining access back into the venous system), serves as a one way valve
What are granular foveolae and where are they normally found?
pits formed from arachnoid granulations that erode bone, usually found in the vicinity of the superior sagittal, transverse and some other dural venous sinuses
Describe the inferior sagittal sinus, its location and boundaries and where it drains.
is smaller than the superior one, runs in the inferior concave free border of the cerebral falx and ends in the straight sinus
Describe the straight sinus, its location and boundaries and where it drains.
formed by the union of the inferior sagittal with the great cerebral vein, runs inferoposteriorly along the line of attachment of the cerebral falx to the cerebellar tentorium, where it joins the confluence of sinuses
Describe the transverse sinus, its location and boundaries and where and what it drains.
pass laterally from the confluence forming a groove in the occipital bones and the posteroinferior angels of the parietal bones, course along the posterolateral attached margins of the cerebellar tentorium and then become the sigmoid sinuses, drains blood from the confluence, usually the left sinus is dominant and larger than the right
Describe the sigmoid sinus, its location and boundaries and where and what it drains.
found in the posterior cranial fossa forming grooves in the temporal and occipital bones, S-shaped route, turns anteriorly then inferiorly as the IJV after traversing the jugular foramen
Describe the occipital sinus, its location and boundaries and where it drains.
lies in the attached border of the cerebellar falx and ends superiorly in the confluence, communicates inferiorly with the internal vertebral venous plexus
Describe the cavernous sinus, its location and boundaries and where and what it drains.
found on each side of the sella turcica of the sphenoid bone, consists of a venous plexus of veins that extends from the superior orbital fissure anteriorly to the apex of the petrous part of the temporal bone posteriorly, receives blood from the superior and inferior ophthalmic veins, superficial middle cerebral vien and sphenoparietal sinus, drains posteroinferiorly through the superior and inferior petrosal sinuses and emissary veins to the pterygoid plexuses, also drains facial vein, characterized by slow flow, triangle of death
How are the internal carotid artery and the cavernous sinus related?
internal carotid can be found inside the cavernous sinus, internal carotid is surrounded by the carotid plexus of sympathetic nerves and CN VI, allows for heat exchange between the warmer internal carotid and cooler cavernous sinus
What CNs are associated with the cavernous sinus?
CN III, IV, VI and two of the three divisions of CN V (V1 and V2) are embedded in the lateral wall of the cavernous sinus, the sinus makes sleeves for everything that passes through it
Describe the superior petrosal sinus, its location and boundaries and where and what it drains.
runs from the posterior ends of the veins making up the cavernous sinus to the transverse sinus at the site where these sinuses curve inferiorly to form the sigmoid sinuses, lies in the anterolateral attached margin of the cerebellar tentorium, which attaches to the superior border of the petrous part of the temporal bone
Describe the inferior petrosal sinus, its location and boundaries and where and what it drains.
commence at the posterior end of the cavernous sinus inferiorly, runs in a groove between the petrous part of the temporal bone and the basilar part of the occipital bone, the inferior petrosal sinuses drain the veins of the lateral cavernous sinus directly into the origin of the IJVs
Describe the basilar plexus.
connects the inferior petrosal sinuses and communicates inferiorly with the internal vertebral venous plexus
What are emissary veins and what purpose do they serve?
connect the dural venous sinuses with veins outside the cranium, valveless with flow of blood usually away from brain, include the frontal, parietal, mastoid and posterior condylar emissary veins
What purpose do arteries of the dura have?
supply more blood to the calvaria than to the dura itself, includes the middle meningeal artery
Describe the course of the middle meningeal artery.
a branch of the maxillary artery, enters the cranium through the foramen spinosum, runs laterally in the fossa, and turns suerpoanteriorly on the greater wing of the sphenoid where it divides into anterior and posterior branches, the anterior branch runs superiorly to the pterion and then curves posteriorly to ascend toward the vertex of the cranium, posterior branch runs posterosuperiorly and ramifies over the posterior aspect of the cranium
What is the blood supply to the dura?
meningeal branches of the ophthalmic arteries (branch of internal carotid artery), branches of the occipital arteries (branch of external carotid), and small branches of the vertebral arteries
What purpose do the veins of the dura have?
they accompany the meningeal arteries, often in pairs, the middle meningeal veins accompany the middle meningeal artery, leave the cranial cavity through the foramen spinosum or foramen ovale and drain into the pterygoid plexus
What is the nerve supply of the dura?
innervated by meningeal branches arising directly or indirectly from CN V, the anterior meningeal branches of the ethmoidal nerves (CN V1), and the meningeal branches of the maxillary (CN V2) and mandibular (CN V3) nerves supply the dura of the anterior cranial fossa, the latter two also supply the dura of the middle cranial fossa
What does the tentorial nerve supply?
tentorial nerve (branch of the ophthalmic nerve) supplies the roof of the posterior cranial fossa and posterior part of the cerebral falx
What is the innervation to the anterior cerebral falx?
anterior cerebral falx innervated by ascending branch of the anterior meningeal branches
What is the innervation of the dura of the floor of the posterior cranial fossa?
receives sensory fibers from the spinal ganglia of C2 and C3 carried by those spinal nerves transferred to and traveling centrally with CN X and XII
Describe the pain innervation of the dura
pain fibers are most numerous where arteries and veins course in the dura, pain arising from the dura is generally referred, perceived as a headache arising in cutaneous or mucosal regions supplied by the involved cervical nerve or division of CN V
What is the origin of the leptomeninx?
develops from a single layer of mesenchyme surrounding the embryonic brain, becoming the parietal part (arachnoid) and visceral part (pia) of the leptomeninx
what are arachnoid trabeculae?
pass between the arachnoid and the pia, give the arachnoid its name, composed of flattened fibroblasts that bridge the subarachnoid space
Describe the arachnoid.
contains fibroblasts, collagen fibers and some elastic fibers, the arachnoid is thick enough to be manipulated with forceps, the avascular arachnoid is held against the inner surface of the dura by the pressure of the CSF, does not follow the contours of gyri and sulci
Describe the pia
thin, highly vascularized membrane, difficult to see, gives the surface of the brain a shiny appearance, adheres to the surface of the brain and follows all its contours including the sulci and gyri
Describe the subdural hematoma.
hematomas at this junction are usually caused by extravasated blood that splits open the dural border cell layer, blood does not collect within a pre-existing space, but rather creates a space at the dura-arachnoid junction, usually follows a blow to the head, typically venous in origin and commonly results from tearing a superior cerebral vein as it enters the superior sagittal sinus
Describe the subarachnoid hemorrhage
escape of blood (usually arterial) into the subarachnoid space, results from rupture of a saccular aneurysm (such as from the internal carotid artery), results in meningeal irritation, a severe headache, stiff neck and often loss of consciousness
Where does the blood supply to the brain derive from and where does it lie?
derives from the internal carotid and vertebral arteries, lie in the subarachnoid space, venous drainage occurs via cerebral and cerebellar veins that drain to the adjacent dural sinuses
What is the origin and distribution of the internal carotid artery?
ascends through the cartodi canal in the petrous part of the temporal bone, turns horizontally and medially in the carotid canal toward the apex of the temporal bone and emerges from the canal superior to the foramen lacerum to enter the cranial cavity, courses anteriorly through the cavernous sinus
1. origin-common carotid artery at superior border of thyroid cartilage
2. distribution-gives branches to walls of cavernous sinus, pituitary gland, and trigeminal ganglion, provides primary supply to brain
What CNs are associated with the course of the internal carotid artery in the cranial cavity?
course in the cavernous sinus with CN VI and in close proximity to CN III and IV running the carotid groove on the side of the body of the sphenoid
what is the origin and distribution of the anterior cerebral artery?
1. origin-internal carotid artery
2. distribution-cerebral hemispheres, except for occipital lobes, most of the medial ans superior surfaces of the brain and the frontal pole, part of the motor cortex as well as the hip and lower limb
what is the origin and distribution of the anterior communicating artery?
1. origin-anterior cerebral artery
2. distribution-cerebral arterial circle of Willis
what is the origin and distribution of the middle cerebral artery?
1. origin-continuation of internal carotid artery distal to anterior cerebral artery
2. distribution-most of the lateral surface of cerebral hemispheres, temporal pole, primary motor cortex, sensory cortex, Brocca’s and Wernike’s areas
what is the origin and distribution of the vertebral artery?
begins in the root of the neck as the first branches of the first part of the subclavian artery, left usually larger than the right, ascends through the transverse foramina of the first six cervical vertebrae, perforates the dura and arachnoid and passes through the foramen magnum, the two unite and form the basilar artery
1. oring-subclavian artery
2. distribution-cranial meninges and cerebellum
What is the origin and distribution of the basilar artery?
1. origin-formed by the union of vertebral arteries
2. distribution-brainstem, cerebellum and cerebrum
What is the course of the basilar artery?
ascends the clivus (the sloping surface from the dorsum sellae to the foramen magnum), through the pontocerebellar cistern to the superior border of the pons, it ends by dividing into the two posterior cerebral arteries
What is the origin and distribution of the posterior cerebral artery?
1. origin-terminal branche of the basilar artery
2. distribution-inferior aspect of cerebral hemisphere and occipital lobe, vision
What is the origin and distribution of the posterior communicating artery?
1. origin-posterior cerebral artery
2. distribution-optic tract, cerebra peduncle, internal capsule and thalamus
Describe the circle of Willis.
on the ventral surface of the brain, an important anastomosis at the base of the brain between the four arteries that supply the brain, from anterior to posterior composed of:
1. anterior communicating artery
2. anterior cerebral arteries
3. internal carotid arteries
4. posterior communicating arteries
5. posterior cerebral arteries
How much of the total cardiac output does the brain receive?
brain accounts for only about 2.5% of the body weight but the brain receives about 1/6 of the cardiac output and 1/5 of the O2 consumed by the body at rest
Describe the venous drainage of the brain.
the thin walled, valveless veins pierce the arachnoid and meningeal layer of the dura to end in the nearest dural venous sinuses which ultimately drain in the IJV
What veins in the brain drain into what sinuses?
1. superior cerebral veins-drain into the superior sagittal sinus
2. inferior and superficial middle cerebral veins-drain into the straight, transverse and superior sagittal sinuses
3. great cerebral vein-merges with the inferior sagittal sinus to form the straight sinus
4. superior and inferior cerebellar veins-drains the cerebellum and drains into the transverse and sigmoid sinuses
What happens if a cerebral artery is blocked?
stroke
What are the warning signs of a stroke?
1. sudden, severe headache with no known cause
2. unexplained dizziness, unsteadiness or sudden falls, especially with any of the other signs
3. sudden dimness or loss of vision, particularly in one eye
4. sudden difficulty speaking or trouble understanding speech
5. sudden weakness or numbness of the face, arm or leg on one side of the body
What are the different types of stroke?
there is an ischemic stroke (which can be further subdivided into a thromotic (due to a blood clot that blocks flow of blood into the brain) and embolic (fatty plaque breaks away and flows to brain where it blocks an artery)) and a hemorrhagic stroke (due to an aneurysm in a blood vessel in the brain or a saccular anurysm)
What is the most common cause of strokes?
spontaneous cerebrovascular accidents (CVA), such as cerebral thrombosis, cerebral hemorrhage, cerebral embolism, and subarachnoid hemorrhage
What are the treatments for the different types of stroke?
1. ischemic strokes-use tPA (tissue plasminogen activator), antiplatelet drugs, anticoagulants
2. hemorrhagic strokes-surgery to repair the ruptured vessels and to insert a stent
What bones make up the anterior cranial fossae?
is the shallowest of the three cranial fossa, made by the frontal bone anteriorly, the ethmoid bone in the middle and the body and lesser wings of the sphenoid posteriorly
What foramina exit through the anterior cranial fossa and what are its contents?
1. foramen cecum-nasal emissary vein
2. cribriform foramina in cribriform plate-axons of olfactory cells in olfactory epithelium that form olfactory nerves
3. anterior and posterior ethmoidal foramina-vessels and nerves with the same names
What bones make up the middle cranial fossae?
composed of the sella turcica of the sphenoid bone, the greater wings of the sphenoid and squmous parts of the temporal bones laterally and the petrous part of the temporal bones posteriorly
What foramina exit through the middle cranial fossae?
1. optic canals-CN II and ophthalmic arteries
2. superior orbital fissure-ophthalmic veins, CN V1, III, IV and VI and sympathetic fibers
3. foramen rotundum-CN V2
4. foramen ovale-Cn V3 and accessory meningeal artery
5. foramen spinosum-middle meningeal artery and vein and meningeal branch of CN V3
6. foramen lacerum-internal carotid artery and its accompanying sympathetic and venous plexuses
7. groove of greater petrosal nerve-greater petrosal nerve and petrosal branch of middle meningeal artery
8. carotid canal-internal carotid artery and vein
What bones make up the posterior cranial fossae?
formed mostly by the occipital bone, but the dorsum sellae of the sphenoid marks its anterior border centrally and the petrous and mastoid parts of the temporal bones contribute its anterolateral walls
What foramina exit through the posterior cranial fossae?
1. foramen magnum-medulla and meninges, vertebral arteries, CN XI, dural veins, anterior and posterior spinal arteries
2. jugular foramen-CN IX, X, XI, superior bulb of internal jugular vein, inferior eptrosal and sigmoid sinuses and meningeal branches of ascending pharyngeal and occipital arteries
3. hypoglossal canal-CN XII
4. condylar canal-emissary veins that passes from sigmoid sinus to vertebral veins in neck
5. mastoid foramen-mastoid emissary vein from sigmoid sinus and meningeal branch of occipital artery
6. internal acoustic meatus-CN VII and VIII
Where do CNs VII-XII exit?
exit the brainstem and the skull in the posterior fossa
Where do CNs III-VI exit?
exit the brainstem in the posterior fossa and travel intradurally through the cavernous sinus into the middle fossa where they leave the skull through the superior orbital fissure, they have a long course and are susceptible to damage
Which CN has the longest course?
CN VI because it comes off further inferior off the brain stem, the most commonly injured CN
Where does CN VII exit?
it exits through the internal acoustic meatus, then passes through the geniculate ganglion (sensory nerve cells within the facial nerve)
Give a general overview of the orbit in terms of shape, margins and location of the eyeball.
1. each orbit is pyramidal shape
2. the orbital margin is at the base, directed anterolaterally
3. the apex is at the optic canal, directed posteromedially
4. the medial walls are parallel and about 25 mm apart, are separated by the ethmoidal sinuses and the upper parts of the nasal cavity
5. the lateral walls are at right angles to each other
6. the eyeball lies in the anterior half of the orbit
What bones make up the orbit?
frontal, zygomatic, maxillary, lacrimal, ethmoid, sphenoid, palatine
What accessory visual structures are protected by the orbit?
1. eyelids-bound the orbits anteriorly, controlling exposure of the anterior eyeball
2. extraocular muscles-position the eyeballs and raise the superior eyelids
3. nerves and vessels in transit to the eyeballs and muscles
4. orbital fascia surrounding the eyeballs and muscles
5. mucous membrane (conjunctiva) lining the eyelids and anterior aspect of the eyeballs and most of the lacrimal apparatus, which lubricates it
What is the purpose of orbital fat?
fills all spaces in the orbit not occupied by the above structures, thus it forms a matrix in which the structures of the orbit are embedded
What forms the base of the orbit?
outlined by the orbital margin that surrounds the orbital opening which is reinforced to afford protection to the orbital contents, attachment point for the orbital septum, an interrupted fibrous sheet that extends into the eyelids
What forms the roof (superior wall) of the orbit?
approx. horizontal, formed by the orbital part of the frontal bone, separates the orbital cavity from the anterior cranial fossa, also formed by the lesser wing of the sphenoid where the roof is near the apex of the orbit, accommodates the lacrimal gland in the lacrimal fossa anterolaterally
What forms the medial walls of the orbit?
walls on the contralateral sides are parallel, formed by the ethmoid bone (primarily) with contributions from the frontal, lacrimal and sphenoids, indented anteriorly by the lacrimal groove and fossa for the lacrimal sac
What forms the floor (inferior wall) of the orbit?
formed mainly by the maxilla and partly by the zygomatic and palatine bones, shared with the maxillary sinus inferiorly, slants inferiorly from the apex to the inferior orbital margin, demarcated from the lateral by the inferior orbital fissure
What forms the lateral wall of the orbit?
formed by the frontal process of the zygomatic bone and the greater wing of the sphenoid, this is the strongest and thickest wall, it is also the most exposed and vulnerable to direct trauma, its posterior part separates the orbit from the temporal and middle cranial fossae, lateral wall of the contralateral side is almost perpendicular
Where is the apex of the orbit?
is at the optic canal (where the optic nerve and ophthalmic artery exit) in the lesser wing of the sphenoid just medial to the superior orbital fissure
What is the widest part of the orbit?
it corresponds to the equator of the eyeball, an imaginary line encircling the eyeball equidistant from its anterior and posterior parts
What is periorbita?
lines the bones forming the orbit, is the periosteum of the orbit, continuous at the optic canal and superior orbital fissure with the periosteal layer of the dura, also continuous over the orbital margins and through the inferior orbital fissure with the periosteum covering the external surface of the cranium (pericrium) and with the orbital septa at the orbital margins, with the fascial sheaths of the extraocular muscles and with the orbital fascia that forms the fascial sheath of the eyeball
Describe what a blowout fracture is, what bone is broken and how is it caused.
occurs following a blow to the bony rim or the globe (eyeball), caused by an indirect injury that displaces the orbital walls, when the floor of the orbit is fractured, the eyeball can sink lower on the affected side, it is possible for structures in the orbit to get caught in the fracture pieces, if inferior rectus is trapped, the damaged eye cannot be elevated properly, when asked to look up can’t because of muscle, not nerve damage
What are the three layers of the eyeball?
1. outer (fibrous) layer-composed of opaque sclera (continuation of the dura) and translucent cornea
2. middle (vascular, pigmented) layer-composed of the choroid (which has pigmented epithelium associated with it), ciliary body (composed of smooth muscle, like iris, and gets only parasympathetic innervation) and iris (is what makes the pupil, has both sympathetic and parasympathetic innervation, pigmented layer, the sphincter and dilator of the pupil)
3. inner layer-composed of the retina (both rods and cones) that has both optic and non-visual parts
What are the CT layers that surround these three layers of the eyeball?
composed posteriorly of bulbar fascia (which forms the true socket for the eyeball) and anteriorly of bulbar conjunctiva, surrounds the eyeball allowing its movement within the orbit
Describe the sclera.
tough opaque part of the fibrous layer (coat) of the eyeball covering the posterior 5/6 of the eyeball, provides shape and resistance as well as attachment for both the extraocular and intrinsic muscles of the eye, is the white of the eye
Describe the cornea
translucent covering that covers the anterior 1/6 of the eyeball
Describe the choroid.
a dark, reddish brown layer, found between the sclera and the retina, forms the largest part of the vascular layer of the eyeball and lines most of the sclera
What is the vascular lamina? capillary lamina of the choroid?
vascular lamina are the larger vessels that are located externall (near) the sclera, the capillary lamina are the finest of vessels located innermost, supplies the avasucular light sensitive layer of the retina, responsible for the red eye during photos, continuous with the ciliary body
Describe the ciliary body.
muscular and vascular layer that connects the choroid with the circumference of the iris, provides attachment for the lens, controls thickness and focus of lens via contraction and relaxation of its smooth muscle
What is the purpose of the ciliary processes?
they are folds located on the internal surface of the ciliary body and it makes aqueous humor
What is the flow of aqueous humor?
comes from the ciliary process to scleral venous sinus via the schlemm’s canal, found in both the anterior and posterior chamber, goes from posterior chamber to anterior, blockage of Schlemm’s canal can lead to INC pressure that may lead to glaucoma
Describe the iris and the muscles that regulate their constriction/dilation.
lies on the anterior surface of the lens, a thin contractile diaphragm with a central aperture (pupil) that transmits light, controlled by the involuntary sphincter pupillae (parasympathetic, closes the pupil, slower responses to environment but constriction is instantaneous) and dilator pupillae (sympathetic, opens the pupil, faster responses to environment but slower dilation)
Describe the retina.
the inner layer of the eyeball, consists of an optic part and a non-visula part
What is the purpose of the optic part of the retina?
it is sensitive to visual light, composed of a neural layer and a pigment cell layer, neural layer is light receptive, pigment cell layer consists of a single layer of cells that reinforces the light absorbing proptery of the choroid in reducing the scattering of light in the eyeball
What is the purpose of the non-visual part of the retina?
an anterior continuation of the pigment cell layer and a layer of supporting cells over the ciliary body (ciliary part of the retina) and the posterior surface of the iris (iridial part of the retina), respectively
Describe the fundus.
it is the posterior part of the eyeball, contains the optic disc
What is the macula lutea?
a yellow structure located lateral to the optic disc, it is a small oval area of the retina with special photoreceptor cones that is specialized for acuity of vision, is the area of most acute vision, when get further and further from the macula density of rods INC and cones DEC, cones are for acute vision
What is the fovea centralis
found at the center of the macula lutea, a depression that is the area of most acute vision
What is the ora serrata?
it is an irregular border slightly posterior to the ciliary body, marks the anterior termination of the light-receptive part of the retina
What is the blood supply to the retina?
except for the cones and rods, supplied by the central artery of the retina, a branch of the ophthalmic artery, rods and cones get nutrients from the capillary lamina of the chroid (choriocapillaries), drains via the central vein of the retina
What are the anterior and posterior chambers and what separates the two?
anterior chamber is the space between the cornea anteriorly and the iris/pupil posteriorly, posterior chamber is the space between the iris/pupil anteriorly and the lens and ciliary body posteriorly, iris separates the two chambers from each other
What are the components of the refractive media of the eyeball
cornea, aqueous humor, lens and vitreous humor
Describe the cornea
circular area of the anterior part of the outer fibrous layer of the eyeball, largely responsible for refraction of the light that enters the eye, sensitive to touch, innervated by the ophthalmic nerve, avascular, nourished by the capillary beds at its periphery, aqueous humor and lacrimal fluid
Describe the aqueous humor.
is a clear watery solution that provides nutrients for the avasular cornea and lens, drains into the scleral venous sinus (canal of Schlemm), then removed by limbal plexus (network of scleral veins close to the limbus), then drain into both tributaries of the vorticose and the anterior ciliary veins
Describe the lens.
posterior to the iris and anterior to the vitreous humor of the vitreous body, has a highly elastic capsule anchored by the zonular fibers (suspensory ligament of the lens) to the ciliary body and encircled by the ciliary processes, convexity varies to fine tune the focus of near or distant objects on the retina
What is the ciliary muscle and what is its purpose?
located in the ciliary body and changes the shape of the lens, has attachments around its periphery that pull the lens relatively flat so that its refraction enables far vision, parasympathetics cause it to contract causing constriction of lens, when parasympathetics removed then lens is pulled into its flatter, far-vision shape, when contracts=relaxed (fat) lens, when relax=tensed (flat) lens (for far vision)
What is the vitreous body?
it is colorless, composed of transparent gel that is 99% water, found in the posterior 4/5 of the eyeball posterior to the lens, transmits light and holds the retina in place and supports the lens
What is the optic disc?
it is the entry point of the optic nerve with central retinal vessels, blind spot also located here, is where the sensory fibers and vessels conveyed by the optic nerve enter the eyeball, contains no photoreceptors so is insensitive to light
What is glaucoma?
is INC intraocular pressure (greater than 20-22 mm Hg), caused by a DEC in the drainage of aqueous humor through the scleral venous sinus, causes an INC in pressure, blindness can result from compression of the inner layer of the eyeball (retina) and the retinal arteries
what are the components, location of the nerve cell bodies, cranial exit and main action of CN II (optic)?
1. component-special sensory
2. location of the nerve cell bodies-retina (ganglion cells)
3. cranial exit-optic canal
4. main action-vision from retina
Describe the origin of the optic nerve.
are paired structures that are anterior extension of the forebrain (diencephalon), CNS fiber tracts formed by axons of retinal ganglion cells, cell bodies are in the retina, the central artery and vein of the retina traverse the meningeal layers and course in the anterior part of the optic nerve
Describe the course of the optic nerve
CN II begins where the unmyelinated axons of the retinal ganglion cells peirce the sclerea and become myelinated (deep to the optic disc), the passes posteromedially in the orbit, exiting through the optic canal to enter the middle cranial fossa where it forms the optic chiasm
What is the purpose of the optic chiasm?
it is here where fibers from the medial half of each retina decussate (allowing depth perception), then join the uncrossed fibers from the lateral half of the retina to form the optic tract, therefore fibers from the right halves of both retinas form the left optic tract
What is the purpose of the lateral geniculate bodies?
where most fibers in the optic tract terminate, from here axons are relayed to the visual cortices of the occipital lobes of the brain
Describe the optic nerve in innervation of the orbit.
runs through the optic canal, meningeal dura follows the optic nerve but there is also pia mater and arachnoid present to cover the optic nerve as well, CSF is also present, excess pressure in CSF may lead to papiledema
What nerves that supply the orbit enter through the superior orbital fissure?
those that supply the ocular muscles, include CN III, IV and VI, remember LR6(SO4)3
What are the three branches of the ophthalmic nerve (CN V1)?
frontal, nasociliary, lacrimal, pass through the superior orbital fissure and supply structures related to the anterior orbit (lacrimal gland and eyelids), face and scalp
What is the ciliary ganglion?
is a small group of postsynaptic nerve cell bodies associated with CN V1, located between the optic nerve and the lateral rectus toward the posterior limit of the orbit, gets branches from ciliary ganglion
What are the main nerves that go to the ciliary ganglion?
nasociliary nerve (sensory, an opthalmic branch), short ciliary, oculomotor (parasympathetic), internal carotid plexus (sympathetics)
Where does the ciliary ganglion receive nerve fibers from?
1. sensory fibers from CN V1, via the communicating branch of the nasociliary nerve (the sensory or nasociliary root of the ciliary ganglion
2. presynaptic parasympathetic fibers from CN III via the parasympathetic or oculomtor root of the ciliary ganglion
3. postsynaptic sympathetic fibers from the internal carotid plxus via the sympathetic root of the ciliary ganglion
Describe CN III in innervation of orbit.
CN III divides into inferior and superior division and gives contribution to the ganglion, give it parasympathetic for the constrictor papillae and lens
Where do the short ciliary nerves arise from and what do they innervate?
from the ciliary ganglion and are considered to be branches of CN V1, consist of postsynaptic parasympathetic fibers from the ciliary ganglion, afferent fibers from the nasociliary nerve that pass through the ganglion, and postsynaptic sympathetic fibers that also pass through it, carry parasympathetic and sympathetic fibers to the ciliary body and iris
Where do the long ciliary nerves arise from and what do they innervate?
they are branches of the nasociliary nerve that pass to the eyeball, bypassing the ciliary ganglion, convey postsynaptic sympathetic fibers to the dilator pupillae and afferent fibers from the iris and cornea
Where do the posterior and anterior ethmoidal nerves come from and what do they innervate?
they are branches of the nasociliary nerve arising in the orbit, exit via openings in the lateral wall of the orbit to supply the mucous membrane of the sphenoidal and ethmoidal sinuses and the nasal cavities as well as the dura of the anterior cranial fossa
What is the course of the post-ganglionic sympathetics?
course within oculomotor nerve to innervate superior tarsal muscle that helps elevate upper lid, course as a plexus on internal carotid artery to long and short ciliary nerves to dilator pupillae muscles to dilate pupil
What is the course of the somatomotor axons?
originate in brainstem and pass through III to levator palpebrae superioris muscle
What is the course of the parasympathetics to the orbit?
parasympathetics to the sphincter pupillae muscle which constricts pupil in reponse to light, parasympathetics to ciliary body thicken lens for accommodation to near vision
What is the innervation of the lacrimal gland?
by VII, all the parasympathetic glands of the head are by seven except the parotid, out on VII, through the internal auditory meatus, gives off the greater petrosal branch near geniculate ganglion and synapses at the pterygopalatine ganglion
Describe the course of the greater petrosal branch of VII.
jumps onto V2 and then V1 to reach the lacrimal gland
Which vessels do you visualize with an opthalmoscope?
1. choroid gets supply from the ciliary vessels to the iris, ciliary muscle, sclera and rods and cones of retina
2. rest of the retina gets a blood supply from the central artery of the retina, blockage of the central artery results in immediate irreversible blindness
What is papilledema?
caused by an INC in CSF pressure that can be detected by looking through the pupil at the optic disc with an opthalmoscope, slows venous return from retina causing edema of the retina, papilledema is the swelling of the optic disc
What is the origin, insertion, innervation and main action of the levator palpebrae superioris?
1. origin-lesser wing of sphenoid bone, superior and anterior optic canal, broadens into two laminar aponeuroses, superificial lamina attaches to the skin of the superior eyelid and deep lamina to the superior tarsus
2. insertion-superior tarsus and skin of superior eyelid
3. innervation-oculomotr nerve, deep layer (superior tarsal muscle) is supplied by sympathetic fibers
4. main action-elevates superior eyelid, is opposed most of the time by gravity
What is the superior tarsal muscle?
is the smooth muscle of the deep lamina of the levator palpebrae superioris, produce additional widening of the palpebral fissure during a sympathetic response, attaches to the tarsal plate, maintains resting tone to help hold up the eyelid, innervated by the SNS
What and where is the common tendinous ring?
a fibrous cuff that surrounds the optic canal and part of the superior orbital fissure, four of the extraocular muscles originate from this annulus tendineus, found at the apex of the orbit
What is the origin, insertion, innervation, and main action of the superior oblique
1. origin-body of sphenoid bone
2. insertion-its tendon passes through a fibrous ring or trochlea, changes its direction and inserts into sclera deep to superior rectus muscle
3. innervation-CN IV
4. main action-abducts, depresses and medially rotates eyeball
What is the origin, insertion, innervation and main action of the inferior oblique muscle?
1. origin-anterior part of floor of orbit
2. insertion-slcera deep to lateral rectus muscle
3. innervation-CN III
4. main action-abducts, elevates and laterally rotates eyeball
What is the origin, insertion, innervation and main actions superior rectus
1. origin-common tendinous ring
2. insertion-sclera just posterior to corneoscleral junction
3. innervation-CN III
4. main action-elevates, adducts and rotates eyeball medially
What is the origin, insertion, innervation and main action of the inferior rectus?
1. origin-common tendinous ring
2. insertion-sclera just posterior to corneoscleral junction
3. innervation-CN III
4. main action-depresses, adducts and rotates eyeball laterally
What is the origin, insertion, innervation and main action of the medial rectus?
1. origin-common tendinous ring
2. insertion-sclera just posterior to corneoscleral junction
3. innervation CN III
4. main action-adducts eyeball
What is the origin, insertion, innervation and main action of the lateral rectus?
1. origin-common tendinous ring
2. insertion-sclera just posterior to corneoscleral junction
3. innervation-CN VI
4. main action-abducts eyeball
Which extraoccular muscles abduct?
superior oblique, inferior oblique, lateral rectus
which extraoccular muscles adduct?
superior rectus, inferior rectus and medial rectus
which extraoccular muscles depress?
superior oblique and inferior rectus
which extraoccular muscles elevate?
inferior oblique, superior rectus
which extraoccular muscles rotate medially?
superior oblique and superior rectus
which extraoccular muscles rotate laterally?
inferior oblique and inferior rectus
In the transverse axis, what movements are involved?
elevation and depression, any muscle that attaches to the top and comes from the back is an elevator, any muscle that attaches to the bottom and comes from the back is a depressor
In the anteroposterior axis, what movements are involved?
lateral and medial rotation
In the vertical axis, what movements are involved?
abduction and adduction
If your patient cannot look up how can you determine which muscle is dysfunctional?
if adduct the eye then can't look up only the inferior oblique can work, if abduct the eye then can't look up only the superior rectus can work
What is one cause of double vision?
rotation of the eyeball around an AP axis accommodate changes in the tilt of the head, if there is an absence of these movements resulting from nerve lesions, then this can lead to double vision
Describe the fascial sheath of the eyeball.
envelops the eyeball from the optic nerve nearly to the corneoscleral junction forming the actual socket for the eyeball, pierced by the extraoccular muscles
What are the medial and lateral check ligaments?
are triangular expansions from the sheaths of the medial and lateral rectus muscles, are attached to the lacrimal and zygomatic bones respectively, limit abduction and adduction, prevent the eye from moving too far from side to side
What is the suspensory ligament of the eyeball?
formed from the check ligaments with the fascia of the inferior rectus and inferior oblique, supports the eyeball, forms a sling that helps the globe in place
What is the episcleral space?
it is a potential space between the eyeball and the fascial sheath, allows the eyeball to move inside the cup-like sheath
What is the origin, course and distribution of the ophthalmic artery?
1. origin-internal carotid artery
2. course and distribution-traverse optic foramen to reach orbital cavity
What does the ophthalmic artery do?
it is the main blood supply to the orbit, is a branch of the internal carotid artery
What are the branches of the ophthalmic artery in the orbit?
central artery or retina, supraorbital, supratrochlear, lacrimal, dorsal nasal, short posterior ciliaries, long posterior ciliaries, posterior ethmoidal, anterior ethmoidal
What course and distrubtion and central artery of retina?
pierces dural sheath of optic nerve and runs in nerve to eyeball, branches radiate from center of optic disc, supplies optic retina (except cones and rods), terminal branches are end arteries, provide the only blood supply to the internal aspect of the retina
What is the course and distribution of the lacrimal artery?
passes along superior border of lateral rectus muscle to supply lacrimal gland, conjunctiva and eyelids
What is the course and distribution of the short posterior ciliary arteries?
pierce sclera at periphery of optic nerve to supply choroid, which in turn supplies cones and rods of optic retina, 6 of them
What is the course and distribution of the long posterior ciliary arteries?
pierce sclera to supply ciliary body and iris
What is the origin, course and distribution of the anterior ciliary artery?
1. origin-muscular (rectus) branches of the ophthalmic artery
2. course and distribution-pierces sclera at attachments of rectus muscles and forms network in iris and ciliary body, anastamoses with the long posterior ciliaries
What is the origin, course and distribution and infraorbital artery?
1. origin-thrid part of maxillary artery
2. course and distribution-passes along infraorbital groove and foramen to face
Describe the venous drainage of the orbit.
1. through the superior and inferior ophthalmic veins, which pass through the superior orbital fissure and enter the cavnerous sinus
2. central vein of the retina enters the cavernous sinus directly but may join one of the ophthalmic veins
3. the vorticose veins from the vascular layer of the eyeball drain into the inferior ophthalmic veins
4. the scleral sinus is a vascular structures encircling the anterior chamber of the eyeball through which the aqueous humor is returned to the blood circulation
What is the purpose of the eyelids and lacrimal fluids?
both protect the cornea and eyeball from injury and irritation, eyelids also protect it from excessive light and help spread the lacrimal fluid, eyelid movement is from lateral to medial
What are the two types of conjunctiva and what purpose do they serve?
1. palpebral conjunctiva-covers the eyelids internally, a transparent mucous membrane
2. bulbar conjunctiva-continuous with the palpebral part where it is reflected onto the eyeball, bulbar is thin and transparent and attaches lossely to the anterior surface of the eyeball, is loose and wrinkled over the sclera, adherent to the periphery of the cornea
3. sac that prevents things from going all the way back to the brain, forms a closed sac
Where do the superior and inferior conjunctival fornices come from?
are deep recesses that are reflection lines of the palpebral conjunctiva onto the eyeball
What is the conjunctival sac?
a space bound by the palpebral and bulbar conjunctivae, is a closed space when the eyelids are closed but opens via an anterior aperture (palpebral fissure) when the eye is open), enables the eyelids to move freely over the surface of the eyeball as they open and close
What are the tarsal plates?
are rigid structures found on the inside of the eyelids strengthening them, is bigger in the upper eyelid, allowing for flipping eyelids inside out, rigid so can hold the eyelid upside down, also has tarsal gland associated with it, acts as an attachment point for levator palpebrae superioris and superior tarsal muscle
What do the tarsal glands do?
secrete a sebaceous type fluid that keeps eyelids from sticking together and also keeps the watery substance of the lacrimal gland from moving out of the eyelid, only works if there is normal tear production, if too high then flows over the edge
What are the medial and lateral palpebral commissures?
where the superior and inferior eyelids meet, define the angles of the eye
What are the medial and lateral palpebral ligaments?
1. medial palpebral ligament-found between the nose and medial angle of the eye, connects the tarsi to the medial margin of the orbit, acts as insertion and origin for orbicularis oris
2. lateral palpebral ligament-attaches the tarsi to the lateral margin of the orbit
What structures make up the lacrimal apparatus?
lacrimal gland, lacrimal ducts, lacrimal canaliculi, nasolacrimal duct
What are the lacrimal glands?
secrete lacrimal fluid (which has bacteriocidal enzyme lysozyme), moistens the surfaces of the conjunctiva and cornea, provides some nutrients and dissolved O2 to the cornea, found in the fossa for the lacrimal gland in the superorlateral par of each orbit
What are the different parts of the lacrimal gland?
there is a superior orbital and inferior palpebral part, divided by the lateral expansion of the tendon of the levator palpebrae superioris
Describe the parasympathetic nerve supply to the lacrimal gland.
fluid production is stimulated by parasympathetic impulses form CN VII, presynaptic fibers from the greater petrosal nerve and then by the nerve of the pterygoid canal to the pterygopalatine ganglion where they synapse with the cell body of the postsynaptic fiber
Describe the sympathetic nerve supply to the lacrimal gland.
vasoconstrictive, postsynaptic sympathetic fibers are brought form the superior cervical ganglion by the internal carotid plexus and deep petrosal nerve, join the parasympathetics to form the nerve of the pterygoid canal and traverse the ganglion
What does the zygomatic nerve do for innervation to the lacrimal gland?
is a branch from the maxillary nerve, brings both types of fibers ot the lacrimal branch of the ophthalmic nerve, by which they enter the gland
Where do the lacrimal ducts transfer lacrimal fluid to?
convey fluid from the lacrimal glands to the conjunctival sac
What purpose do the lacrimal canaliculi serve?
drain lacrimal fluid from the lacrimal lake (triangular space at the medial angle of the eye where the tears collect) to the lacrimal sac
What purpose does the nasolacrimal duct have?
it is the dilated superior part of the nasolacrimal duct and conveys the lacrimal fluid to the inferior nasal meatus, from here goes posteriorly to the floor of the nasal cavity to the nasopharynx and are swallowed
What causes ptosis?
can occur if either levator palpebrae superioris or the superior tarsal muscle is denervated
What is the origin of the extraocular muscles?
preotic somites
What are some symptoms of Horner’s syndrome?
is injury to or loss of sympathetic fibers from superior cervical ganglion, leads to:
1. loss of dilator pupillae -> constricted pupil
2. loss of superior tarsal muscle -> ptosis
3. loss of vasoconstriction -> flushed skin
4. loss of sweat glands -> dry skin
5. GVE-sympathetic to dilator pupillae muscle, parasympathetics to ciliary muscle and sphincter pupillae muscle
Describe the light reflex.
in on II out on III, shine light in patients eyes (optic n) and pupil should constrict (parasympathetics via III) via sphincter pupillae muscle
Describe the accommodation reflex.
for near vision, need to round up lens to INC focal position, in on CN II, out on III, as patient looks from a far to near object (optic n), lens should thicken for focusing on near object by contraction of ciliary muscles (parasympathetics via III)
Describe the corneal blink
sensation is via touch, in on V1, out on VII
Describe the visual blink
in on V2 out on VII
Describe the papillary light reflex.
in on II out on III
Describe the tearing reflex.
sensory, in on V out on VII
What are the three components of the ear, what are their components and purposes?
1. external ear-consists of the auricle & external auditory meatus, responsible for capturing and funneling sound (mostly in the vertical axis)
2. middle ear-is an air-filled cavity behind the ear durm, consists of 3 bones (malleus, incus, stapes) that transfer ear drum vibrations to the oval window and fluid behind the oval window, also contains the auditory (Eustachian) tube
3. inner ear-contains the fluid filled cochlea (which has hair cells that connect with CN VIII, splits into cochlear and vestibular part) and the vestibular apparatus, holds sensory hair cells for hearing and balance
What is the embryological origin of the external auditory meatus, middle ear, auditory tube, malleus, incuse and stapes?
1. branchial cleft 1 gives rise to the external auditory meatus
2. branchial pouch 1 gives rise to the middle ear and the auditory tube
3. bronchial arch 1 cartilage gives rise to the malleus and incus (the auditory ossicles are the first bones to be fully ossified during development and are essentially mature at birth)
4. bronchial arch 2 gives rise to the stapes
What is the embryological origin of the inner ear?
otic placode-a thickening of surface ectoderm, it invaginates to form otic pit/vesicle-membranous labyrinth, hair cells, ganglion cells
What is the structure and purpose of the external ear?
its walls are cartilaginous laterally and bony medially (temporal bone), contains ceruminous glands that produce wax which is antibacterial, its purpose is to collect sound (most optimally in the speech range, where it actually amplifies it), helps to localize sound in the vertical axis
Describe the auricle.
is composed of an irregularly shaped plate of elastic cartilage covered by thin skin, composed of many elevations and depressions including the concha and helix
Where and what composes the lobule of the auricle?
is the earlobe, is a non-cartilaginous structure that consists of fibrous tissue, fat and blood vessels, easily pierced for blood samples and inserting earrings
What is the arterial supply to the auricle?
mainly from the posterior auricular and superifical temporal arteries
What is the innervation to the skin of the auricle?
mainly the great auricular (branch of cervical plexus, supplying the cranial (medial) surface and posterior part of the lateral surface) and auriculotemporal nerves (branch of V3, supplies the skin of the auricle anterior to the external acoustic meatus), sensory fibers to external ear is via lesser occipital and great auricular
What is the lymphatic drainage of the auricle?
lateral surface of the superior half of the auricle drains to the superficial parotid lymph nodes, the cranial surface of the superior half drains to the mastoid nodes and deep cervical lymph nodes and the reminder (including lobule) drains into the superficial cervical lymph nodes
Describe the external acoustic meatus.
leads inward through the tympanic part of the temporal bone from the auricle to the tympanic membrane, lateral third is cartilaginous, medial 2/3 is bony and lined with thin skin, has ceruminous and sebaceous glands in the subQ tissue of cartilaginous part that produces cerumen
Describe the tympanic membrane.
~1 cm in diameter, thin, oval semitransparent membrane at the medial end of the external acoustic meatus, separates the meatus and middle ear, covered with thin skin externally and mucous membrane internally
Describe the orientation of the tympanic membrane.
is tilted down and forward, like the position of tiger ears when they are ready to pounce, membrane has a concavity toward the meatus, with a cone-like depression with a peak (umbo)
Describe the innervation of the tympanic membrane
external surface is supplied mainly by the auriculartemporal nerve (branch of CN V3), some innervation is supplied by a small auricular branch of the vagus (CN X), the internal surface of the tympanic membrane is supplied by the glossopharyngeal nerve (CN IX)
What happens when stick Q-tip too far into the external acoustic meatus?
can cause cough via via CN X
Describe the middle ear (tympanic cavity).
is an air filled compartment (via the auditory tube), contains the middle ear ossicles (M-I-S), the bones transfer the vibration of the tympanic membrane to the inner ear, lined with mucous membrane, composed of two parts: tympanic cavity proper (space directly internal to the tympanic membrane) and epitympanic recess (space superior to the membrane)
What is the purpose of the middle ear?
it amplifies the sound signal, it makes up for the energy which is lost as sound moves from air into a liquid medium
What structures is the middle ear continuous with?
mastoid air cells (can get inflammation of the mastoid air cells leading to mastoiditis) and nasopharynx via the auditory tube
What are the boundaries/walls of the middle ear cavity?
1. tegmental wall (roof)-formed by a thin plate of bone (tegmen tympani), sepeartes cavity from dura on the floor of the middle cranial fossa
2. jugular wall (floor)-formed by bone that separates the cavity from the superior bulb of the internal jugular vein
3. membranous wall (lateral)-formed by tympanic membrane and parts of the lateral bony wall of the epitympanic recess
4. labyrinthine wall (medial)-formed by promontory, basal turn of cochlea and oval and round window, separates cavity from internal ear
5. carotid wall (anterior)-formed by openings for the auditory tube and canal for the tensor tympani, separates cavity from carotid canal
6. mastoid wall (posterior)-formed by the aditus to the mastoid antrum, connects cavity to the mastoid air cells, canal for facial nerve descends between the posterior wall and the antrum, medial to the aditus
What is the mastoid antrum
is a cavity in the mastoid process of the temporal bone
What is the promontory in the middle ear?
it is a bump (round swelling) found on the basal turn of the cochlea, the tympanic plexus sits on it and supplies the main innervation to the middle ear cavity
What is the nerve supply to the tympanic plexus and what is its course?
most come from CN IX, tympanic nerve exits skull through jugular foramen, recurs off CN IX and gets into the middle ear cavity through the tympanic canaliculus and forms the plexus on the promontory, after innervating the middle ear cavity, the nerve plexus reforms into a single nerve (lesser petrosal), lays on top of the petrous portion and exits through foramen ovale to get to parotid gland (synapses at otic ganglion)
What other nerves are present in the middle ear?
1. chorda tympani-branch of CN VII, runs over the handle of the malleus, if ear drum is ruptured, may also destroy the chorda tympani causing loss of taste of the anterior 2/3 of the tongue
2. facial nerve-through the stylomastoid foramen
Describe the auditory tube (Eustachian, pharyngotympanic tube).
connects the tympanic cavity to the nasopharynx, where it opens posterior to the inferior nasal meatus, posterolateral 1/3 is bony and remainder is cartilaginous, lined with mucous membrane
What is the function of the auditory tube?
equalizes pressure in the middle ear with the atmospheric pressure therby allowing free movement of the tympanic membrane
What opens and closes the auditory tube?
opened by the expanding girth of the belly of the levator veli palatine as it contracts longitudinally, pushing against one wall while the tensor veli palatine pulls on the other, allows for popping of the eardrums
What is the blood supply and venous and lymphatic drainage to the auditory tube?
derived from the ascending pharyngeal artery (branch of the external carotid) and the middle meningeal and artery of the pterygoid canal (branches of the maxillary artery), veins drain into the ptergyoid venous plexus, lymphatic drain to the deep cervical nodes
What is the innervation of the auditory tube?
arise from the tympanic plexus which is formed by the fibers of CN IX, anteriorly may also receive fibers from the pterygopalatine ganglion
What happens when the auditory tube is blocked?
since the middle ear is lined with mucous membrane, a block at the auditory tube can lead to an INC in secretions by the mucous membrane, there is lymphoid tissue right at the entrance of the auditory tube, it can inflame in children causing ear infection, may bulge out because of the excess fluid in the middle ear, becomes red and vibrations DEC
What is otitis media?
is middle ear infection, is very common, microorganisms enter the middle ear via the auditory tube, common in children whose auditory tube is angled slightly superiorly towards the nasal cavity, middle ear fills with fluid, tympanic membrane gets red and inflamed, kid starts getting bacteria in the middle ear cavity, causes pressure, highly innervated middle ear so very painful, when kid lies down is when it is more painful
What is the oval window?
where the stapes attaches, an oval opening on the labyrinthine wall of the tympanic cavity leading to the vestibule of the bony labyrinth
Describe the auditory ossicles.
are synovial joints, can become inflamed, hard bone covered with mucous membrane but lack a surrounding layer of osteogenic periosteum, INC foce but DEC amplitude of the vibrations from the tympanic membrane
Describe the malleus (hammer).
handle attaches to the tympanic membrane, head lies in the epitympanic recess, moves with the membrane, head articulates with the incus, tendon of the tensor tympani inserts into its handle near the neck, chorda tympani passes the medial surface of the neck
Describe the incus (anvil).
articulates with both the malleus and stapes, body lies in the epitympanic recess, short limb is connected by a ligament to the posterior wall of the tympanic cavity
Describe the stapes (stirrup).
smallest ossicle, head articulates with the incus, base fits into the oval window, the base is much smaller than the tympanic membrane, thus the vibratory force of the stapes is INC approx. 10 times over that of the tympanic membrane
What are the two small skeletal muscles that alter movement of the ossicles?
1. tensor tympani-goes to the handle of the malleus (which is attached to the tympanic membrane) and makes the membrane somewhat concave from the outside, DEC vibrations of tympanic membrane, arises from the cartilaginous part of the auditory tube, supplied by CN V3
2. stapedius-pulls on the stapes and tightens the stapedius on the foot plate of the oval window, also DEC intensity of vibration by preventing excessive movement of the stapes, is inside the pyramidal eminence, arises from a foramen in the apex of the eminence and inserts on the neck of the stapes, supplied by CN VII
3. both are protective for loud, long standing sounds, but not for short duration sounds
What is the round windows purpose?
acts as a pressure-relief valve for the cochlear apparatus, when pull on the oval window, fluid bulges the membrane of the round window relieving some of the pressure
Describe the inner ear.
movement of the stapes against the oval window causes vibration of fluid in the inner ear, sensory cells in the cochlea respond providing you with balance and hearing, sensory cells in the vestibular apparatus respond to movements of the head and provide you with balance, components include the cochlear apparatus (for hearing) and the semicircular canals (composed of utricle and saccule, for balance), is buried in the petrous part of the temporal bone the internal ear consists of the sacs and ducts of the membranous labyrinth
What are the different types of labyrinths?
there is a membranous labyrinth containing endolymph (for balance), this is suspended within the perilymph (for hearing) filled bony labyrinth either by delicate filaments or by the substantial spiral ligament
Describe the bony labyrinth.
is a series of cavities (cochlea, vestibule and semicircular canals) contained within the otic capsule of the petrous part of the temporal bone, is fluid filled space surrounded by otic capsule
What is the cochlea?
shell shaped part of the bony labyrinth, contains the cochelar duct (concerned with hearing), has a spiral canal that starts at the vestibule and makes 2.5 turns around the modiolus (bony core that contains blood vessels and distribution of cochlear nerve), large basal turn produces the promontory of the labyrinthine wall
How does the cochlea work?
has hair cells that respond to different frequencies depending on their location on the basilar membrane, the basilar membrane is tuned to different frequencies, high frequency is near the base and low frequency is near the apex
Describe how cochlear implants work.
1. a stimulating electrode, with multiple active sites, is pushed into the scala tympani
2. sounds/speech are detected by a microphone
3. the info is sent to a speech processor and converted into electrical code
4. the coded signal is sent to a transmitting coil that sends radio waves the skin to the implant
5. the implant sends the appropriate frequency info to the appropriate active site and electrically drives the CN VIII nerves that innervated that part of the cochlea
What is the vestibule of the bony labyrinth?
small oval chamber that contains the utricle and saccule and parts of the balancing apparatus (vestibular labyrinth), lateral wall has oval window, continuous with the cochlea anteriorly, the semicircular canals posteriorly and the posterior cranial fossa by the aqueduct of the vestibule (which opens into the internal acoustic meatus, responsible for transmitting the endolymphatic duct and two small blood vessels)
Describe the semicircular canals.
they communicate with the vestibule of the bony labyrinth, lie posterosuperior to the vestibule, occupy three planes in space (anterior, posterior and lateral canals), within the canals are the semicircular ducts
Describe the membranous labyrinth.
consists of sacs and ducts that are suspended by the bony labyrinth, contains endolymph (similar in composition to intracellular fluid) and surrounding perilymph (like extracellular fluid) that fills the remainder of the bonyy labyrinth, composed of two divisions: vestibular and cochlear, and three semicircular ducts
Describe the vestibular labyrinth.
contains the utricle and saccule, two small communicating sacs in the vestibule of the bony labyrinth
Describe the cochlear labyrinth
contains the cochlear duct in the cochlea
Describe the semicircular ducts
open into the utricle via five openings, utricle communicates with the saccule through the utriculosaccular duct from which the endolymphatic duct arises, each has an ampulla at one end containing a sensory ampullary crest
Where are the hair cells of the cochlea located?
in the maculae, are innervated by fibers of the vestibular division of the vestibulocochlear nerve, the primary sensory neurons are in the vestibular ganglia which are in the internal acoustic meatus
What is the purpose of the ampullary crest?
are sensors for recording movements of the endolymph in the ampulla resulting from rotation of the head in the plane of the duct, the hair cells of the crest like those of the maculae stimulate primary sensory neurons whose cell bodies are in the vestibular ganglion
What is the cochlear duct?
a spiral tube closed at one end, suspended in the cochlear canal between the spiral ligament on the external wall of the cochlear canal and the osseous spiral lamina
What are the receptos of auditory stimuli?
they are the spiral organ of Corti, it is situated on the basilar membrane, overlaid by tectorial membrane, contains hair cells, the tips of which are embedded in the tectorial membrane, the organ is stimulated to respond by deformation of the cochlear duct induced by the hydraulic pressure waves in the perilymph, which ascend and descend in the surrounding scalae vestibule and tympani
Describe the internal acoustic meatus.
canal that runs laterally within the petrous part of the temporal bone, passageway for CN VII, VIII and its division, and blood vessels, the vestibulocochlear nerve divides near the lateral end of the internal acoustic meatus into two parts, a cochlear nerve and a vestibular nerve
Describe the course of CN VIII in terms of the inner ear.
enters the temporal bone and actually never leaves the skull, enters the internal auditory meatus, branches to the vestibular and cochlear branches, special somatosensory cell bodies are in the vestibular and spiral ganglia, is only sensory and has a vestibular and cochlear (spiral) ganglion
Describe the course of CN VII in terms of the inner ear.
enters the internal auditory meatus, forms a T at the geniculate ganglion, greater petrosal nerve passes anteromedially, main trunk of the nerve passes posterolaterally into the facial canal, as it descends toward the stylomastoid forament it gives off the chorda tympani and the nerve to the stapedius
What is the frenulum of the tongue and what are some problems associated with it?
it is the attachment of the tongue to the floor of the oral cavity, allows the anterior part of the tongue, a sublingual caruncle is present on each side of the base of the frenulum that includes the opening of the submandibular duct from the submandibular salivary gland, in some kids, the frenulum may be short so they cannot suck properly, so have to do a frenulumectomy
What are the palatine tonsils?
referred to as the tonsils, are masses of lymphoid tissue, one on each side of the oropharynx, each tonsil is in a tonsillar sinus bounded by the palatoglossal and palatopharyngeal arches and the tongue
What holds the palatine tonsil in its place?
behind the palatine tonsil is a fold called the palatopharyngeal arch, it inserts into the pharynx, has a muscle (palopharyngeal muscle), mucous membrane that blocks off infection that stops infection from going into the pharyngeal space (buccopharyngeal membrane)
What is the most common way to get infection into the retropharyngeal space?
abcesses at the back of the tonsil
How many permanent teeth and deciduous teeth are there?
1. there are 32 permanent teeth-16 upper, 16 lower, 2 central incisors, 2 lateral incisors, 2 canines, 4 premolars and 6 molars
2. there are 20 deciduous teeth-10 upper and 10 lower, 2 central incisors, 2 lateral incisors, 2 canines, 4 molars
What is the vasculature to the teeth?
the superior and inferior alveolar arteries, branches of the maxillary artery, supply the maxillary and mandibular teeth, alveolar veins with the same names and disbtribution accompany the arteries, lymphatic vessels from the teeth and gingivae pass mainly to the submandibular lymph nodes
What is the innervation of the teeth?
the named branches of the superior (CN V2) and inferior (CN V3) alveolar nerves give rise to dental plexuses that supply the maxillary and mandibular teeth, the lingual nerve is closely related to the medial aspect of the 3rd molars, therefore, caution is taken to avoid injuring this nerve during extraction
What is the palate?
it forms the arched roof of the mouth and the floor of the nasal cavities, it separates the oral cavity from the nasal cavities and the nasopharynx, the part of the pharynx superior to the soft palate, consists of hard palate anteriorly and soft palate posteriorly
Describe the hard palate.
anterior 2/3 of the palate, mostly filled by tongue, has a bony skeleton formed by the palatine processes of the maxillae and the horizontal plates of the palatine bones
Describe the soft palate.
posterior 1/3 of the palate, moveable, suspended from the posterior border of the hard palate, no bony skeleton but does have an anterior aponeurotic part (palatine aponeurosis, formed from the expanded tendon of the tensor veli palatini) and a posterior muscular part, uvula hangs from here, continuous with the wall of the pharynx and is joined to the tongue and pharynx by the palatoglossal and palatopharyngeal arches
How does the soft palate move to accommodate swallowing?
the soft palate initially is tensed to allow the tongue to press against it, squeezing the bolus of food to the back of the mouth, the soft palate is then elevated posteriorly and superiorly against the wall of the pharynx thereby preventing passage of food into the nasal cavity
What are the incisive papilla?
they are located posterior to the maxillary incisor teeth in the midline, is an elevation of the mucosa that lies directly anterior to the underlyling incisive fossa, the incisive foramina are the openings of the incisive canals that transmit the nasoplatine nerves and vessels
What are the transverse palatine folds (rugae)?
they radiate laterally from the incisive papilla, assist with manipulation of food during mastication
What is the palatine raphe?
passes posteriorly from the incisive papilla, a narrow whitish streak that marks the site of fusion of the embryonic palatine processes
What are the muscles of the soft palate?
tensor veli palatine, levator veli palatine, palatoglossus, palatopharyngeus, musculus uvulae
What is the superior and inferior attachment, innervation and main action of the tensor veli palatini?
1. superior attachment-scaphoid fossa of medial pterygoid palte, spine of sphenoid bone and cartilage of pharyngotympanic tube
2. inferior attachment-palatine aponeurosis
3. innervation-medial pterygoid nerve (a branch of mandibular nerve) via otic ganglion
4. main action-tenses soft palate and opens mouth of pharyngotympanic tube during swallowing and yawning
What is the superior and inferior attachment, innervation and main action of the levator veli palatini?
1. superior attachment-cartilage of pharyngotympanic tube and petrous part of temporal bone
2. inferior attachment-palatine aponeurosis
3. innervation-pharyngeal branch of vagus nerve via pharyngeal plexus
4. main action-elevates soft palate during swallowing and yawning
What is the superior and inferior attachment, innervation and main action of the palatoglossus?
1. superior attachment-palatine aponeurosis
2. inferior attachment-side of tongue
3. innervation-pharyngeal branch of vagus nerve via pharyngeal plexus
4. main action-elevates posterior part of tongue and draws soft palate onto tongue
What is the superior and inferior attachment, inneravtion and main action of the palatopharyngeus?
1. superior attachment-hard palate and palatine aponeurosis
2. inferior attachment-lateral wall of pharynx
3. innervation-pharyngeal branch of vagus nerve via pharyngeal plexus
4. main action-tenses soft palate and pulls walls of pharynx superiorly, anteriorly and medially during swallowing
What is the superior and inferior attachment, innervation and main action of the musculus uvulae?
1. superior attachment-posterior nasal spine and palatine aponeurosis
2. inferior attachment-mucosa of uvula
3. innervation-pharyngeal branch of vagus nerve (CN X) via pharyngeal plexus
4. main action-shortens uvula and pulls it superiorly
What is the vasculature to the palate?
mainly from the greater palatine artery (branch of the descending palatine artery), greater palatine passes through the greater palatine foramen and runs anteriomedially, also from lesser palatine artery which enters the palate through the lesser palatine foramen and anastomoses with the ascending palatine artery (from facial artery), veins of palate are tributaries of the pterygoid plexus
What is the sensory innervation to the palate?
sensory nerves of palate are branches of the maxillary nerve that branch from the pterygopalatine ganglion, greater palatine nerve supplies the gingivae, mucous membrane and glands of most of the hard palate, nasopalatine nerve supplies the mucous membrane of the anterior part of the hard palate, lesser palatine nerves supply the soft palate, palatine nerves accompany the arteries and veins through the palatine foramina
What are some tests for hypoglossal nerve damage?
atrophy due to denervation, leads to deviation upon protrusion on same side of atrophy, if have tongue atrophy on right side, then on protrusion, tongue moves out and to the right
What are the extrinsic muscles of the tongue?
originate outside the tongue and attach to it, mainly move the tongue but they can alter its shape as well, include the genioglossus, hyoglossus, sytloglossus, and palatoglossus
What is the shape, attachments and main actions of the genioglossus?
1. shape-fan-shaped muscle, constitutes the bulk of the tongue
2. proximal attachment-via a short tendon from superior part of mental spine of mandible
3. distal attachment-entire dorsum of tongue, inferior most and posterior most fibers attach to body of hyoid bone
4. main action-depresses tongue, posterior part pulls tongue anteriorly for protrusion, unilateral contraction deviates tongue to contralateral side
What is the shape, attachment and main action of the hyoglossus?
1. shape-thin, quadrilateral muscle
2. proximal attachment-body of greater horn of hyoid bone
3. distal attachment-inferior aspects of lateral part of tongue
4. main action-depresses tongue, pulling its sides inferiorly, helps retrude (shorten) tongue
What is the shape, attachment and main action of the styloglossus?
1. shape-small, short triangular muscle
2. proximal attachment-anterior border of distal styloid process, stylohyoid ligament
3. distal attachment-sides of tongue posteriorly, interdigitating with hyoglossus
4. main action-retrudes tongue and curls its sides, working with genioglossus to form a central trough during swallowing
What is the shape, attachment and main action of the palatoglossus?
1. shape-narrow crescent-shaped palatine muscle
2. proximal attachment-palatine aponeurosis of soft palate
3. distal attachment-enters posterolateral tongue transversely, blending with intrinsic transverse muscle
4. main action-elevate posterior tongue, depress soft palate, can also constrict isthmus of fauces (throat)
What are the intrinsic muscles of the tongue?
muscles that have thair attachments entirely within the tongue and are not attached to bone, include the superior and inferior longitudinal, transverse and vertical muscles of the tongue, alter the shape of the tongue
What is the shape, attachments and main action of the superior longitudinal muscle of the tongue?
1. shape-thin layer deep to mucous membrane of dorsum
2. proximal attachment-submucosal fibrous layer and medina fibrous septum
3. distal attachment-margins of tongue and mucous membrane
4. action-curls tongue longitudinally upward, elevating apex and sides of tongue, shortens (retrudes) tongue
What is the shape, attachment and main action of the inferior longitudinal muscle of the tongue?
1. shape-narrow band close to inferior surface
2. proximal attachment-root of tongue and body of hyoid bone
3. distal attachment-apex of tongue
4. main action-curls tongue longitudinally downward, depressing apex, shortens (retrudes) tongue
What is the shape, attachment and main action of the transverse muscle of the tongue?
1. shape-deep to superior longitudinal muscle
2. proximal attachment-median fibrous septum
3. distal attachment-fibrous tissue at lateral lingual margins
4. main action-narrows and elongates (protrudes) tongue
What is the shape, attachment and main action of the vertical muscle of the tongue?
1. shape-fibers intersect transverse muscle
2. proximal attachment-submucosal fibrous layer of dorsum of tongue
3. distal attachment-inferior surface of borders of tongue
4. main action-flattens and broadens tongue
What is the dorsum of the tongue?
it is the posterosuperior surface of the tongue, located partly in the oral cavity and partly in the oropharynx, characterized by the V shaped terminal sulcus, the angle of which points posteriorly to the foramen cecum (remnant of the proximal part of the thyroglossal duct)
What are the different types of lingual papillae in the tongue?
1. vallate papillae-large and flat topped, directly anterior to the terminal sulcus, surrounded by deep trenches studded with taste buds, ducts of serous glands open into trenches
2. foliate papillae-small lateral folds of the lingual mucosa, poorly developed in humans, have taste buds
3. filiform papillae-long and numerous, contain afferent nerve endings that are sensitive to touch
4. fungiform papillae-mushroom shaped pink spots, scattered among the filiform papillae but are most numerous at the apex and margins of the tongue, have taste buds
What is the lingual tonsil?
is lymphoid tissue found in the posterior part of the tongue, has no lingual papillae
What are the motor nerves to the tongue?
vagus supplies the palatoglossus via the pharyngeal plexus, hypoglossal nerve supplies all other muscles of the tongue
What are the sensory nerves to the tongue?
for general sensation (touch and temperature) the mucosa of the anterior 2/3 of the tongue is supplied by the lingual nerve (a branch of CN V3), taste for anterior 2/3 is via chorda tympani nerve (via CN VII) which joins the lingual nerve and runs anteriorly in its sheath, chorda tympani also gives some parasympathetics which join the lingual nerve and innervate the submandibular and sublingual gland, mucous membrane of the posterior 1/3 of the tongue and the vallate papillae are supplied by the lingual branch of the glossopharyngeal nerve (CN IX) for both general and special sensation, twigs of the internal laryngeal nerve (via CN X) supply mostly general but some special sensation to a small area of the tongue just anterior to the epiglottis and also carries some parasympathetic secretomotor fibers
Describe the role of the lingual artery in blood supply to the tongue.
derived from the lingual artery which arises from the external carotid artery, has dorsal lingual arteries that supply the hyoglossus muscle and deep lingual arteries that supply the anterior part
Describe the venous drainage of the tongue.
there are dorsal lingual veins and deep lingual veins (which join the sublingual vein) which eventually drain into the IJV
Describe the lymphatic drainage of the tongue.
most converges toward and follows the venous drainage, follows four different routes:
1. lymph from the posterior third drains into the superior deep cervical lymph nodes
2. lymph from the medial part of the anterior two thirds drains directly to the inferior deep cervical lymph nodes
3. lymph from the lateral parts of the anterior two thirds drains to the submandibular lymph nodes
4. the apex and frenulum drain to the submental lymph nodes
What is the phyarnx?
is the superior expanded part of the alimentary system posterior to the nasal and oral cavities, extending inferiorly past the larynx, widest opposite the hyoid and narrowest where it is continuous with the esophagus
What are the boundaries of the pharynx?
it extends from the cranial base to the inferior border of the cricoid cartilage anteriorly and the inferior border of the C6 vertebra posterioly
What are the subdivisions of the pharynx?
nasopharynx-area posterior to nasal cavity (respiratory) and superior to the soft palate, sometimes digestive though (like when someone can spit liquid out of nose)
oropharynx-area posterior to oral cavity (digestive and respiratory)
laryngopharynx-area posterior to larynx (digestive and respiratory)
What are the boundaries of the pharyngeal subdivisions?
1. whole pharynx extends from the base of the skull to C6 vertebra (cricoid cartilage)
2. nasopharynx-behind the nasal cavity down to the uvula, superior to soft palate, posterior extension of the nasal cavity
3. oropharynx-uvula (soft palate) to the tip of the epiglottis
4. laryngopharynx-epiglottis to the cricoid cartilage
What structures are associated with the nasopharynx/soft palate?
1. cartilaginous end of the auditory tube (torus tubarius)
2. levator veli palatine (temporal bone and auditory tube CN X), elevates palate, comes in from the side (from the cartilaginous portion of the tube) but does not open the tube
3. tensor veli palatine (sphenoid bone and auditory tube CN V), attaches to the bony spicule (pterygoid hamulus), opens the auditory tube as it tenses the palate
What is the torus tubarius?
is the swelling containing lymphoid tissue
What are the choanae?
they are two openings that allows the nose to open into the nasopharynx
What is the tonsillar ring of tissue?
associated with the oral and nasal cavity, is the first line of defense of invasion of bacteria to the GI tract and respiratory tree, elements of the tonsillar ring are resorbed beginning around puberty, found around the superior part of the pharynx, composed of the palatine, lingual and pharyngeal tonsils, the anteroinferior part of the ring is formed by the lingual tonsil
Describe the pharyngeal tonsils.
referred to as adenoids when enlarged, in the mucous membrane of the roof and posterior wall of the nasopharynx
What is the pharyngotympanic tube?
it is the opening of the auditory tube into the nasopharynx, can be occluded if there is an enlarged pharyngeal tonsil obstructing the nasal choanae
What are the salphingopharyngeal muscles?
muscles responsible for opening the pharyngeal orifice of the pharyngotympanic tube during swallowing, covered by the salphingopharyngeal fold
What are the tubal tonsils?
collection of lymphoid tissue in the submucosa of the pharynx near the pharyngeal orifice of the pharyngotympanic tube
What is the torus tubarius?
is the swelling containing lymphoid tissue, posterior to this and the salpingopharyngeal fold is a slit like projection (pharyngeal recess) which extends laterally and posteriorly
What are the boundaries of the oropharynx?
bounded by the soft palate superiorly, the base of the tonue inferiorly, and the palatoglossal and palatopharyngeal arches laterally
What structures are associated with the oropharynx?
includes the posterior 1/3 of the tongue, palatine tonsil between palatoglossal and palatopharyngeal arch and the valleculae (recess at base of the tongue)
What are the three stages associated with swallowing (deglutition)?
1. voluntary-bolus is compressed against palate and pushed into the oropharynx mainly by movements of the muscles of the tongue and soft palate
2. involuntary and rapid, soft palate is elevated sealing off the nasopharynx from the oropharynx and laryngopharynx, suprahyoid and longitudinal pharyngeal muscles contract elevating the larynx
3. involuntary-sequential contraction of all three constrictor muscles forces the food bolus inferiorly into the esophagus
What is the valleculae?
recess at the back of the tongue, where popcorn gets stuck
What are the palatine tonsils? where does it lie?
collections of lymphoid tissue on each side of the oropharynx in the interval between the palatine arches, does not fill tonsillar sinus, lies in the tonsillar bed (formed by the superior constrictor of the pharynx and the pharyngobasilar fascia)
What are the boundaries of the laryngopharynx?
lies posterior to the larynx extending from the superior border of the epiglottis and the pharyngoepiglottic folds to the inferior border of the cricoid cartilage where it narrows and becomes continuous with the esophagus, posteriorly related to bodies of C4-C6, posterior and lateral walls formed by the middle and inferior constrictor muscles, internal walls formed by the palatopharynges and tsylopharynges muscles
What structures are associated with the laryngopharynx?
epiglottis, laryngeal inlet (aditus) and piriform fossa (recess)
What is the piriform fossa?
a small mucosa-lined depression of the laryngopharyngeal cavity on either side of the laryngeal inlet, branches of the internal laryngeal and recurrent laryngeal nerve lie deep to the mucous membrane of the piriform fossa and are vulnerable to injury when a foreign body lodges here
What are the pharyngeal constrictor muscles?
1. superior constrictor-anteriorly joins buccinators at the pterygomandibular raphe, between pterygoid plate and mandible, form lateral wall of oral cavity
2. middle constrictor-attaches/arises to the hyoid bone, spans superiorly and inferiorly
3. inferior constrictor-ends inferiorly at the cricoid cartilage and thyroid cartilage, continuous with esophagus
4. all these muscles are somewhat associated with the different regions of the pharynx, are the external circular layer of pharyngeal muscles
What fascia surrounds the pharyngeal constrictor muscles?
strong internal pharyngobasilar fascia, thin external buccopharyngeal fascia (which is continuous with the deep cervical fascia)
What is the origin, insertion, innervation and main action of the superior constrictor muscle?
1. origin-pterygoid hamulus, pterygomandibular raphe, posterior end of mylohyoid line of mandible and side of tongue
2. pharyngeal tubercle on basilar part of occipital bone
3. pharyngeal branch of vagus (CN X) and pharyngeal plexus
4. main action-constrict walls of pharynx during swallowing
What is the origin, insertion, innervation and main action of the middle constrictor muscle?
1. origin-stylohyoid ligament and greater and lesser horns of hyoid
2. insertion-pharyngeal raphe
3. innervation-pharyngeal branch of vagus (CN X) and pharyngeal plexus plus branches of external and recurrent laryngeal nerves of vagus
4. main action-constrict walls of pharynx during swallowing
What is the origin, insertion, innervation and main action of the inferior constrictor muscle?
1. origin-oblique line of thyroid cartilage and side of cricoid cartilage
2. insertion-crciopharyngeal part encircles pharyngoesophageal junction without forming a raphe
3. innervation-pharyngeal branch of vagus and pharyngeal plexus, plus branches of external and recurrent laryngeal nerves of vagus
4. main action-constrict walls of pharynx during swallowing
What is the pterygomandibular raphe?
where the buccinators and superior pharyngeal constrictor attach
What are the extrinsic muscles of the pharynx?
1. palatogpharyngeus
2. stylopharyngeus
3. salpingopharyngeus
4. are the internal, mainly longitudinal layer of muscles
What is the origin, insertion, innervation and main action of the palatopharyngeus muscle?
1. origin-hard palate and palatine aponeurosis
2. insertion-posterior border of lamina of thyroid cartilage and side of pharynx and esophagus
3. innervation-pharyngeal branch of vagus and pharyngeal plexus
4. main action-elevate (shorted and widen) pharynx and larynx during swallowing and speaking
What is the origin, insertion, innervation and main action of the salpingopharyngeus muscle?
1. origin-cartilaginous part of pharyngotympanic tube
2. insertion-blends with palatopharyngeus
3. innervation-pharyngeal branch of vagus and pharyngeal plexus
4. main action-elevate (shortedn and widen) pharynx and larynx during swallowing and speaking
What is the origin, insertion, innervation and main action of the syltopharyngeus?
1. origin-styloid process fo temporal bone
2. insertion-posterior and superior borders of thyroid cartilage with palatopharyngeus,
3. innervation-CN IX
4. main action-elevate (shorten and widen) pharynx and larynx during swallowing and speaking
What is the blood supply to the pharynx?
from the tonsillar artery (branch of the facial artery), passes through the superior constrictor muscle and enters the inferior pole of the tonsilalos get seom from the ascendin palatine, lingual, descending palatine and ascending pharyngeal arteries, drained by external palatine vein
Describe the innervation of the pharynx.
fibers of contributing nerves are embedded in the buccopharyngeal fascia on posterior wall of pharynx, note pharyngeal branch of X (is the main motor supply to the muscles), gets its innervation from three sources which converge on the posterior lateral wall as the pharyngeal plexus, they are:
1. sensory from CN IX (small portion of nasopharynx is from V2-ignore it), sensory, supply most of the mucosa of all three parts of the pharynx
2. motor from CN X via pharyngeal branch(except one muscle), motor to all muscles of pharynx except one (stylopharyngeus) as well as innervating muscles of soft palate (except tensor veli palatini, via CN V3), branches include superior laryngeal nerve, internal branch and external branch and recurrent laryngeal nerve
3. sympathetic from the sympathetic chain, gag reflex via CN IX/X
Where do the tonsilar nerves come from?
derived from the tonsillar plexus of nerves formed by branches of the glossopharyngeal and vagus nerves
What is the innervation of the cervical esophagus?
somatic motor and senstory to the upper half and parasympathetic and visceral sensory to the lower half, somatic fibers from the recurrent laryngeal nerves and vasomotor fibers from the cervical sympathetic trunk through the plexus around the inferior thyroid artery
What is the larynx?
the complex organ of voice production composed of nine cartilages connected by membranes and ligaments and containing the vocal folds, at C3-C6, connects inferior part of the pharynx with the trachea, most important function is guarding the air passages, especially during swallowing when it serves as the sphincter of the lower respiratory tract
What is the aditus? what are its boundaries?
laryngeal inlet, it is the opening to the larynx, between the epiglottis and posterior wall of the larynx (renoid and cricoid cartilage), can change in size depending on the position of the epiglottis (when swallowing the larynx will elevate, muscles pull up on the hyoid and pharyngeal constrictors that can help elevate it)
How is the size of the aditus regulated?
it gets smaller if push epiglottis back and elevate laryngeal apparatus, but never gets completely closed
What is the vestibule and what are its boundaries?
is from the aditus to the vestibular folds, two sets of vestibular folds (vestibular (false vocal) folds and true vocal folds)
What is the ventricle found in the larynx? what are its boundaries?
recess extending laterally from the middle part of the laryngeal cavity between vestibular and vocal folds, structure that is important for opening and closing of the true vocal folds (when singing), it applies tension and closing pressure to the vocal folds, the pressure of air underneath causes them to open and vibrate, frequency of vibration is dependent on tension on them, found between the true and false vocal folds
What is the infraglottic cavity and what are its boundaries?
it is the space below the true folds, inferior border is the cricoid cartilage, it is continuous with the lumen of the trachea
What are the nine cartilages of the larynx?
there are three single (thyroid, cricoid and epiglottic) and three paired (arytenoid, corniculate and cuneiform)
Describe the thyroid cartilage.
2/3 shield, anterior is complete, posterior is open, posterior has a superior (towards the hyoid bone, attached to it by thyrohyoid membrane) and inferior horn (attached to cricoid cartilage via the cricothyroid joints, point of articulation between the thyroid and cricoid)
What is the laryngeal prominence?
where the right and left inferior 2/3s fuse anteriorly
Describe the cricoid cartilage.
large posteriorly, the arytenoids sit on it, smaller but thicker and stronger than the thyroid cartilage, only complete ring of cartilage to encircle any part of the airway, attaches to the inferior margin of the thyroid by the median circothyroid ligament and to the first tracheal ring by the cricotracheal ligament
Describe the arytenoids.
are found on the lateral part of the superior border of the posterior aspect of the cricoid, has a muscular process (sits posteriorly and to the side, responsible for spinning the arytenoid cartilage on top of the cricoid cartilage, serves as a lever for posterior and lateral cricoarytenoid muscles) and vocal process (goes forward, attached to the thyroid cartilage by vocal ligament)
Where do the vocal ligaments stretch to?
extend from the junction of the laminae of the thyroid cartilage anteriorly to the vocal process of the arytenoid cartilage posteriorly, make up the submucosal skeleton of the vocal folds
Where do the arytenoids pass to and what is its main action?
have a ligament that passes forward to the thyroid cartilage, amount of adduction of this ligament determines the size of the rima
Describe the epiglottic cartilage.
consists of elastic cartilage, gives flexibility to the epiglottis, forms the superior part of the anterior wall and the superior margin of the inlet
Describe the thryohyoid membrane.
found between the thyroid cartilage and hyoid bone, houses the internal branch of the superior laryngeal nerve, ends with ends with the superior laryngeal artery (branch of superior thyroid)
What nerve is most important for the cough reflex?
the internal branch of the superior laryngeal nerve
Describe the cricothyroid membrane.
a membrane that is between the thyroid and cricoid ligament, below the true vocal folds, this is where a cricothyrotemy would be performed
Describe the cricothyroid joint.
it is a synovial joint, articulates between the bases of the arytenoid cartilages and the superolateral surfaces of the lamina of the cricoid cartilage, movement occurs around the horizontal transverse axis, it tilts the thyroid cartilage anteriorly and cricoid superiorly, allows the arytenoid to slide toward or away from one another, to tilt anteriorly and posteriorly and to rotate, important in approximating, tensing and relaxing the vocal folds
Describe the cricoarytenoid joint.
is a synovial joint with a delicate capsular ligament, movements include rotation around vertical axis and gliding movements of ab/adduction, for each axis the net result is abduction/adduction of the vocal ligaments
What is the rima?
the slit between the true vocal folds, its shape varies according to the position of the vocal folds, during ordinary breathing it is narrow and wedge shaped, during forced respiration it is wide and kit shaped
What is the glottis?
the true vocal folds + the rima, is the vocal apparatus of the larynx
What does the free edge of the quadrangular membrane form?
its free edge forms the false vocal folds, it is a thin, submucosal sheet of CT that extends between the lateral aspects of the arytenoid and epiglottic cartilages
What does the free edge of the conus elasticase form? what are some of its features?
has a free edge facing superiorly, makes the true vocal fold and vocal ligament, has a mucous membrane
Describe the false vocal fold.
vestibular fold, lies superior to the vocal fold and extends from the thyroid cartilage to the arytenoid cartilage, play little or no part in voice production, they are protective in function
How doe the vocal folds create sound?
produce audible vibrations when their free margin are closely apposed during phonation and air if forcibly expired intermittently, changes in pitch due to variations in the tension and length of the vocal folds, the width of the rima and the intensity of the expiratory effort
What are the extrinsic laryngeal muscles?
move the larynx as a whole, include the infrahyoid muscles and the suprahyoid muscles
What are some examples of the muscles of the vocal folds and their actions?
cricothyroids (tensor), posterior cricoarytenoids (abductor), lateral arytenoids (adductors), transverse arytenoids (adductors), thyroarytenoids (relaxors), all the vocal cord movers are adductors except the posterior cricoarytenoid (this is important for opening the airway), innervation may be different but all from vagus
What is the only muscle of the vocal folds that is not innervated by the recurrent laryngeal nerve?
main tensor (cricothyroid)
What are some examples of the muscles of the laryngeal inlet and their actions?
are muscles that are arching up in the quadrangular membrane, when tighten and contract take the laryngeal opening and sneak it down, prevent food from entereing the adicus, include the transverse and oblique arytenoids and tyroepiglottic
What is the origin, insertion, innervation and main action of the cricothyroid muscle?
1. origin-anterolateral part of the cricoid cartilage
2. insertion-inferior margin and inferior horn of thyroid cartilage
3. innervation-external laryngeal nerve (from CN X)
4. main action-stretches and tenses vocal ligament
What is the origin, insertion, innervation and main action of the thyroarytenoid?
1. origin-lower half of posterior aspect of angle of thyroid laminae and cricothyroid ligament
2. insertion-anterolateral arytenoid surface
3. innervation-inferior laryngeal nerve (terminal part of recurrent laryngeal nerve from CN X)
4. main action-rleaxes vocal ligament
What is the origin, insertion, innervation and main action of the posterior circoarytenoid muscle?
1. origin-posterior surface of lamina of cricoid cartilage
2. insertion-vocal process of arytenoid cartilage
3. innervation-inferior laryngeal nerve (terminal part of recurrent laryngeal nerve from CN X)
4. abducts vocal folds
What is the origin, insertion, innervarion and main action of the lateral cricarytenoid muscle?
1. origin-arch of cricoid cartilage
2. insertion-vocal process of arytenoid cartilage
3. innervation-inferior laryngeal nerve (terminal part of recurrent laryngeal nerve from CN X)
4. main action-adducts vocal folds (interligamentous portion), pull the muscular processes anteriorly, rotating the arytenoid cartilages so that their vocal processes swing medially
What is the origin, insertion, innervation and main action of the transverse and oblique arytenoids?
1. origin-one artenoid cartilage
2. insertion-contralateral arytenoid cartilage
3. innervation-inferior laryngeal nerve (terminal part of recurrent laryngeal nerve from CN X)
4. main action-adduct arytenoid cartilages (adducting intercartilaginous portion of vocal folds, closing posterior rima glottidis)
What is the origin, insertion, innervation and main action of the vocalis muscles?
1. origin-lateral surface of vocal process of artenoid cartilage
2. insertion-ipsilateral vocal ligament
3. innervation-inferior laryngeal nerve (terminal part of recurrent laryngeal nerve from CN X)
4. main action-relaxes posterior vocal ligament while maintaining (or INCing) tension of anterior part
Describe what the adductors and abductors of the larynx do.
move the vocal folds to open and close the rima, include the lateral cricoarytenoid muscles, and transverse and oblique arytenoid muscles (adductors) and the sole abductor posterior circoarytenoid muscles
Describe the position of the rima during whispering.
occurs when the vocal ligaments are adducted by the transverse arytenoid muscles do not act, the arytenoid catilages remain apart and air may bypass the ligaments
Describe what the sphincters of the larynx do.
responsible for closing the laryngeal inlet as a protective mechanism during swallowing, contraction of the lateral cricoarytendois, transverse and oblique arytendois and aryepiglottic muscles brings the folds teogther and pulls the artenoid cartilages toward the epiglottis, occurs reflexively when liquid gets near the laryngeal vestibule
Describe what the tensors of the larynx do.
principle tensors are the cricothyroid muscles which tilt or pull the prominence or angle of the thyroid cartilage anteriorly and inferiorly toward the arch of the cricoid cartilage, causes the vocal ligaments to elongate and tighten, raising the pitch of the voice
Describe what the relaxers of the larynx do.
principles relaxers include the thryoarytenoid muscles, pulls the arytenoid cartilages anteriorly
What is the course of the superior laryngeal nerve?
enters the thyrohyoid, internal branch is sensory to the mucous membrane, external branch is to cricothyroid and pharyngeal constrictors
Describe the blood supply to the larynx.
1. superior laryngeal artery from the superior thyroid, enters the larynx with the superior laryngeal nerve, supplies the internal surface of the larynx
2. cricothyroid artery-small branch of the superior thyroid artier, supplies the cricothyroid muscle
3. inferior laryngeal artery from inferior thyroid follows inferior laryngeal nerve (travels with the recurrent, is a branch of the inferior thyroid), supplies mucous membrane and muscles in the inferior part of the larynx
Describe the venous drainage of the larynx.
superior laryngeal vein joins the superior thyroid vein into the IJV, inferior laryngeal vein joins the inferior thyroid vein which empties into the left brachiocephalic vein
Describe the innervation of the larynx.
motor-all intrinsic muscles by recurrent laryngeal, except circothyroid (external branch of superior laryngeal)
sensory-above vocal folds by superior laryngeal, below vocal folds by recurrent laryngeal
Where does the superior laryngeal nerve arise from and what is its course?
it arises from the inferior vagal ganglion at the superior end of the carotid triangles, divides into two terminal branches the internal laryngeal nerev (sensory and autonomic) and the external laryngeal nerve (motor)
Where does the internal laryngeal nerve arise from and what is its course?
the larger of the terminal branches of the superior laryngeal nerve, pierces the thyrohyoid membrane with the superior laryngeal artery, supplying sensory fibers to the laryngeal mucous membrane of the laryngeal vesitubule and middle laryngeal cavity including the superior surface of the vocal folds
Where does the external laryngeal nerve arise from and what is its course?
the smaller terminal branch of the superior laryngeal, descends posterior to the sternothyroid muscle, first lies on the inferior constrictor muscle but then pierces the muscles contributing to its innervation and continues ot supply the cricothyroid muscle
Where does the inferior laryngeal nerve arise form and what is its course?
it is the continuation of the recurrent laryngeal nerve (from vagus), enters larynx by passing deep to the inferior border of the inferior constrictor muscle and medial to the lamina of the thyroid cartilage, divides into anterior and posterior branches (posterior cricoarytenoid and transverse and oblique arytenoid muscles), primary motor nerve of the larynx, also provides sensory fibers ot the mucosa of the infraglottic cavity
What are the different positions of the vocal folds?
there is a median (closed), paramedian (partially open, for quiet respiration) and full abduction (for large inspiration, requires posterior arytenoids to open vocal folds)
Describe uvular paralysis.
checking the integrity of the uvula is done to check CN X, uvula drawn to nonparalyzed side when patient says AHH
What else is seen in vagus nerve paralysis?
accumulation of saliva in piriform fossa on affected side due to cricophargneal muscle paralysis and inability to swallow
What is the importance of the pterygopalatine fossa?
this small area contains the maxillary nerve, maxillary artery and pterygopalatine ganglion, it connects many areas through numerous openings, sends innervation and blood supply to nasal cavity, palate, teeth and skin of face, inferior to the apex of the orbit
What are the boundaries of the pterygopalatine fossa?
lies between the pterygoid process of the sphenoid posteriorly and the posterior aspect of the maxilla anteriorly, medial wall formed by the palatine bone, roof by the greater wing of the sphenoid, floor is by the pyramidal process of the palatein bone
What structures need to enter the pterygopalatine fossa and how do they get there?
1. maxillary artery-enters through pterygomaxillary fissure (a crack between the mandible and the lateral pterygoid plate), communicates with the infratemporal fossa
2. maxillary nerve (only sensory)-enters through the foramen rotundum, communicates with the middle cranial fossa
3. nerve of the pterygoid canal (parasympathetic and sympathetics)-through the pterygopalatine fossa (medial and inferior to the foramen rotundum)
What structure need to leave the pterygopalatine fossa and how do they leave?
1. infraorbital nerve-leave through the infraorbital canal to the inferior orbital fissure, anterosuperior communication
2. nerves and blood to the palate-comes off ganglion and exits through the palatine canals to the hard and soft palate
3. nerves to the nasal cavity-through the sphenopalatine foramen
Describe the maxillary artery in the pterygopalatine fossa.
after is traverses the infratemporal fossa, it passes over the lateral pterygoid muscles and enters the pterygopalatine fossa, when in the fossa it lies anterior to the pterygopalatine ganglion, gives rise to branches that accompany all nerves in the fossa with the same names, branches include the posterior superior alveolar artery, infraorbital artery, artier of pterygoid canal, pharyngeal branch, descending palatine artery and sphenopalatine artery
posterior superior alveolar artery
descends on maxilla’s infratemporal surface with branches traversing alveolar canals to supply maxillary molar and premolar teeth, adjacent gingival and mucous membrane of maxillary sinus
infraorbital artery
traverses inferior orbital fissure, infraorbital groove, canal and foramen, supplies inferior oblique and rectus muscles, lacrimal sac, maxillary canines and incisors teeth, mucous membrane of the maxillary sinus and skin of infraorbital region of face
artery of pterygoid canal
passes posteriorly through pterygoid canal, supplies mucosa of upper pharynx, pharngotympanic tube, and tympanic cavity
pharyngeal branch of maxillary artery
passes through palatovaginal canal to supply mucosa of nasal roof, nasopharynx, sphenoidal air sinus, and pharyngotympanic tubw
descending palatine artery
descends through palatine canal, dividng into greater and lesser palatine arteries to mucosa and glands of hard and soft palate
sphenopalatine artery
terminal branch of maxillary artery, traverses sphenopalatine foramen to supply walls and septum of nasal cavity, frontal, ethmoidal, sphenoidal and maxillary sinuses and anteriormost palate
What is the course of the maxillary nerve in the pterygopalatine fossa?
once in fosse gives off the zygomatic nerve and two pterygopalatine nerves, then leaves the pterygopalatine fossa through the inferior orbirtal fissure (where it becomes the infraorbital nerve)
Describe the zygomatic nerve.
(which divides into zygomaticofacial and zygomaticotemporal nerves) which supplies general sensation to the lateral region of the cheek and temple as well as parasympathetic secretomotor fibers to the lacrimal gland
What is the purpose of the pterygopalatine nerves off the maxillary nerve?
suspend the parasympathetic pterygopalatine ganglion in the superior part of the pterygopalatine fossa, convey general sensory fibers of the maxillary nerve
Describe the pterygopalatine ganglion.
give off lots of branches including the greater (hard palate) and lesser (soft palate) palatine nerves, there is a synapse at the ganglion, it is a parasympathetic ganglion (similar to otic, submandibular and ciliary ganglia), postganglionic fibers here jump onto a branch of V and head to a target, branch of VII comes in through the pterygoid canal
Where do the parasympathetic fibers to the pterygopalatine ganglion come from?
come from the facial nerve by way of its greater petrosal nerve, this joins with the deep petrosal nerve (as it passes through foramen lacerum) to form the nerve of the pterygoid canal, parasympathetics from here synapse in the pterygopalatine ganglion
What does the deep petrosal nerve do for the pterygopalatine ganglion?
a sympathetic nerve arising from the internal carotid plexus as the artery exits the carotid canal, conveys postsynaptic fibers from nerve cell bodies in the superior cervical sympathetic ganglion to the pterygopalatine ganglion by joining the nerve to the pterygoid canal, fibers do not synapse at the ganglion but pass directly through it into the branches of CN V2, then (w/ the postsynaptic parasympathetics) pass to lacrimal gland, palatine gland and the mucosal glands of the nasal cavity and superior pharynx
What bones make up the lateral wall of the nasal cavity?
ethmoid bone (medial and superior concha is part of this bone), palatine bone, lacrimal bone, maxillary bone, inferior concha, sphenoid bone, frontal bone, nasal bone
What is the composition of the nasal mucosa?
it is firmly bound to the periosteum and perichondrium of the supporting bones and cartilages of the nose, is continuous with the lining of all the chambers with which the nasal cavities communicate
What does the nasal cavity communicate with?
the nasopharynx posteriorly, the paranasal sinuses uspierorly and laterally, and the lacrimal sac and conjunctiva superiorly
What are the boundaries of the nasal cavity?
1. roof-curved and narrow, except at its posterior end, it is divided into three parts (frontonasal, ethmoidal and sphenoidal) named from the bones forming each part
2. floor-wider than the roof and is formed by the palatine processes of the maxilla and the horizontal plates of the palatine bone
3. medial wall-nasal septum
4. lateral wall-formed by the nasal conchae which project inferiorly
What is the purpose of the conchae?
they act as turbinates, break up laminar flow of air into the nose, lined with mucus membrane, also provide large SA for heat exchange
What are the meatuses in the nasal cavity? what are the different types
they are the space under each concha, primary site of draining, there are three of them:
1. superior meatus-has multiple openings for the posterior ethmoidal cells
2. inferior meatus-has the opening for the nasolacrimal duct (drains tears from the lacrimal sac
3. middle meatus-drains frontal sinus (via the ethmoidal infundibulum) and the anterior ethmoidal cells (found on the bump, bulla)
there is also another drainage point above the superior meatus (sphenoethmoidal recess), where sphenoid sinus drains, called the common nasal meatus
What is the nerve supply to the lateral wall of the nasal cavity?
parasympathetics (come from the greater and lesser petrosal) and sympathetics (come from deep petrosal), sensory V2, another branch of the lateral nasal wall is from the anterior ethmoidal, posterior nasal branches from palatine nerves and ganglion
What makes up the nasal septum?
has a large cartilaginous portion (septal cartilage), bony part as well (made up of vomer and perpendicular plate of ethmoid)
What makes the medial wall of nasal cavity?
nasal septum, choanae, nasopharynx
Describe the blood supply of the nasal cavity.
1. sphenopalatine artery-branch of the maxillary artery, goes through the sphenopalatein foramen, way out of the pterygopalatine fossa, gives off nasal branches, also a greater palatine artery
2. there is also a branch from the ethmoidal arteries (branch of the ophthalmic artery) from the orbit, gives anterior and posterior ethmoidal arteries
3. there is also a branch from the facial artery (septal branch of the superior labial artery
Describe the venous drainage of the nasal cavity.
there is a rich submucosal venous plexus deep to the nasal mucosa that drains into the sphenopalatine, facial and ophthalmic veins, also important for thermoregulation (it exchanges heat and warms air before it enters the lung
What is the nerve supply of medial wall?
anterior ethmoidal branch (V1), nasopalatine nerve (V2), nasopalatine nerve in incisive canal
What is the nerve supply to the nasal mucosa?
nasal mucosa is divided into posteroinferior and anterosuperior portions by an oblique line passing approx. through the apex of the nose and the sphenoethmoidal recess, posteroinferior supplied by maxillary nerve (via nasopalatine nerve) and greater palatine nerve (via posterior superior lateral nasal and inferior lateral nasal branches), anterosuperior portion is form ophthalmic nerve (CN V1) by way of the anterior and posterior ethmoidal nerves
How does the nose get its special sensory innervation?
olfactory nerves which arise from cells in the olfactory epithelium in the superior part of the lateral and septal walls of the nasal cavity, central processes pass through the cribriform plate and end in the olfactory bulb (the rostral expansion of the olfactory tract)
Describe the frontal sinus.
between the outer and the inner tables of the frontal bone, posterior to the superciliary arches and the root of the nose, in children by 7 years of age, drains through a fontonasal duct into the ethmoidal infundibulum which opens into the semilunar hiatus of the middle nasal meatus, innervated by supraorbital nerve (CN V1)
Describe the ethmoidal cells (sinuses)
small invaginations of the mucous membrane of the middle and superior nasal meatus into the ethmoid bone between the nasal cavity and orbit, there are anterior, middle and posterior ethmoidal cells, supplied by anterior and posterior ethmoidal branches of the nasociliary nerves (CN V1)
where does the anterior ethmoidal cell drain into?
anterior ethmoidal cells drain directly into the middle nasal meatus through the ethmoidal infundibulum
Where does the middle ethmoidal cell drain into?
middle ethmoidl cells open directly into the middle meatus and form ethmoidal bulla and drain there
Where does the posterior ethmoidal cells drain into?
open directly into the superior meatus
Describe the sphenoidal sinuses.
located in the body of the sphenoid bone and may extend into wings, separated by a septum, only thin plates of bone separate it from optic nerves and optic chiasm, pituitary gland, internal carotid and cavernous sinus, derived from a posterior ethmoidal cell, supplied by the ethmoidal artereies and posterior ethmoidal nerve supply the sphenoidal sinuses
Describe the maxillary sinus.
largest of the paranasal sinuses, occupy boides of maxillae and communicate with the middle nasal meatus, drains by one or more openings (maxillary ostium) into the middle nasal meatus, arterial supply is from superior alveolar branch of the maxillary artery, innervation from anterior, middle and posterior superior alveolar nerves (branches of maxillary nerve)
What are the boundaries of the maxillary sinus?
1. apex-extend toward and often into the zygomatic bone
2. base-forms the inferior part of the lateral wall of the nasal cavity
3. roof-formed by the floor of the orbit
4. floor-formed by the alveolar part of the maxilla,