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19 Cards in this Set
- Front
- Back
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auricle |
- external ear innervation: great auricular nerve (C2-C3) and auriculotemporal nerve (V3) |
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external acoustic meatus |
- external ear - outer 1/3 = cartilaginous - medial 2/3 = bony - contains cerumen (earwax) |
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tympanic membrane |
- boundary b/w external and middle ear - umbo: handle of malleus that causes a depression in the membrane |
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conductive hearing loss |
- caused by perforation of the tympanic membrane - reduces surface area available for transmission of sound to ossicles - causes: infection, trauma to ear, barotrauma, acoustic trauma |
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walls of middle ear cavity: roof floor medial posterior lateral |
- roof: tegmen tympani (petrous temporal bone) - floor: separated from jugular fossa (location of jugular bulb); tympanic branch of CN IX goes here - medial wall: separates tympanic from inner ear; contains tympanic plexus, lesser petrosal nerve, facial nerve; oval window (stapes); round window (secondary tympanic membrane) - posterior wall: mastoid air cells; facial nerve; stapedius muscle - lateral wall: tympanic membrane; handle of malleus |
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otitis media |
- middle ear infection - migration of pathogens from nose/throat to middle ear |
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middle ear bones |
1. malleus - handle embedded in tympanic membrane 2. incus - body articulates with head of malleus; process articulates with stapes 3. stapes (stirrup) - articulates with incus; footplate = oval window |
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middle ear muscles |
- tensor tympani - dampens tympanic membrane (CN V3) - stapedius - dampens stapes movement (CN VII) - attenuates intensity of sounds reaching inner ear |
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bony labyrinth |
- inner ear - fluid-filled cavities within petrous temporal bone - filled with perylimph - cochlea = most anterior part of bony labyrinth - vestibule = central chamber of bony labyrinth; houses utricle and saccule (membranous labyrinth) |
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membranous labyrinth |
- inner ear - fluid-filled sacs and ducts within bony labyrinth - filled with endolymph - contains cochlear duct, with auditory receptors - contains utricle and saccule (linear acceleration) - contains three semicircular canals (rotational movements of the head) |
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vestibular components |
1. semicircular ducts; crista ampullaris = angular movement of the head
2. utricle; macula = gravity and horizontal linear movement of head 3. saccule; macula = gravity and vertical linear movement of head
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cochlear duct |
- located in bony cochlea, but part of membranous labyrinth - has organ of corti = sound receptor |
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endolymphatic duct |
- located in membranous labyrinth - has endolymphatic sac to reabsorb endolymph |
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Meniere's disease |
- excess endolymph in inner ear - common cause of hearing loss - usually only one ear - symptoms: vertigo, severe dizziness, tinnitus, fluctuating hearing loss, pressure/pain |
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sensory hair cells |
- within semicircular ducts - type 1 = flask-shaped; afferent - type II = columnar; efferent - stereocilia = rows of increasing height, tallest = closest to cilium - cupula (gelatinous structure) = top of hair cells; moves with gravity based on endolymph - hair cells bending toward cilium (to tallest) = depolarizing; away (to shortest) = hyperpolarization |
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stria vascularis |
- lining of outer wall of coclear duct - secretes endolymph |
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organ of corti hair cells |
1. inner hair cells - single row receive 90-95% of afferent fibers from cochlear nerve; transduce mechanical signals into electrical signals 2. outer hair cells - 3-5 rows; receive 5-10% afferent fibers; amplify mechanical signal - tectorial membrane sits on top of steriocilia |
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tectorial membreane |
- sound vibrations in inner ear = displacements of basilar membrane and hair cells - displacements create shearing action b/w tectorial membrane and hairs, causing bending |
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sensorineural hearing loss |
noise truama - exposure to loud noises - damages hair cells of organ of corti |
