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76 Cards in this Set
- Front
- Back
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what are the parts of the external ear?
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external auditory canal
hair follicles sebaceous glands ceruminous glands NO SWEAT GLANDS |
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list glands of external ear:
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sebaceous glands
ceruminous glands NO sweat glands |
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what's the middle ear?
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air-filled cavity
~2 mL -has lateral, medial and anterior boundaries -has bony ossicles |
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what's the lateral boundary of the middle ear?
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tympanic membrane (ear drum)
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what's the oval window?
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-where stapes touches and transmits vibration to inner ear
-medial boundary of middle ear -communicates w/ scala vestibuli |
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describe tympanic membrane:
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has stout collagenous connective tissue core..
-Lined on outer surface by:stratified squamous keratinized epithelium -Lined on inner surface by simple cuboidal and simple squamous cells |
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what's most of the middle ear lined by?
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simple squamous epithelial periosteum
-very vascular |
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what does lateral boundary of middle ear have?
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abundant pain afferents
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what's the medial boundary of the middle ear?
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oval window of cochlea
round window of cochlea |
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what's the anterior-inferior boundary of the middle ear?
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auditory tube aka
pharyngotympanic tube aka Eustacian tube |
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what's the func of the anterior-inferior boundary of the middle ear?
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allows the middle ear to equilibrate to ambient pressure
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what are the bony strucs of the inner ear lined by?
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simple squamous epithelium periosteum
-it has potential to produce fluid, but that fluid doesn’t accumulate w/ middle ear b/c middle ear is in continuity w/ middle tube |
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how do you get otitis media?
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Infection causes inflammation of the periosteum and swelling of the auditory tube, closing the lumen and isolating the middle ear.
-Exudate fills the middle ear and pressure builds on the tympanic membrane. |
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why is otitis media common in little kids?
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auditory tube is nearly horizontal and quite short
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any condition that alters pressure in middle ear can:
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can affect hearing by influencing tension of the tympanic membrane.
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why do little kids feel pain when they have otitis media?
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Pain from afferent fibers of tympanic membrane
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how do you treat kids w/ chronic ear infecs?
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put ear tubes in.. Put little segment that drained pus and exudate from middle ear out to external auditory meatus
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what happens to tubes in ear?
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Tubes must either be pulled out or made of biodegradable material and body resorbs it
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how do you hear?
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Malleus inserts on tympanic membrane and has articulation w/ incus, that articulates w/ stapes
When sound waves impinge on tympanic membrane, the mvmnt of tympanic membrane is transmitted thru mvmnt of these three bony ossicles |
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what are the middle ear muscles?
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tensor tympani & stapedius
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any time you feel pain caused by a loud sound...
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you may have suffered permanent hearing loss
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what's the protective acoustic reflex?
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-stapedius dampens transmission of vibration to the oval window from the stapes
-reflex evoked by high amplitude sound • delay ~150 msec |
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what is inner ear?
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membranous labyrinth in bony labyrinth
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describe the bony labyrinth of the inner ear:
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-lined by vascular periosteum
-contains fluid-filled membranous labyrinth |
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describe the membranous labyrinth of the inner ear:
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forms organs of hearing and balance
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what's the organ of hearing?
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cochlea
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what are the parts of the cochlea?
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modiolus
spiral ganglion: CN XIII medial- bony spiral lamina lateral- spiral ligament |
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describe cochlea shape:
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spiral form
2 3/4 turns ~35 mm |
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what's the central core of cochlea?
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modiolous
-house spiral ganglion |
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what's the bony limbus?
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bony spiral lamina of cochlea
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what are the 3 fluid filled compartments of the cochlea?
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scala media
scala vestibuli scala tympani |
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what's the scala media?
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one of fluid filled compartments of cochlea
cochlear duct houses organ of Corti |
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what makes the 3 fluid filled compartments of the Cochlea?
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basilar membrane
vestibular membrane |
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what's the bony spiral lamina?
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bony limbus
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describe endolymph in Cochlea?
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-fills scala media
-made by stria vascularis via active transport -fills all of membranous labyrinth from cochlea to sacule and eutricle and semicircular canals |
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describe stria vascularis:
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-on lateral wall
-tall cuboidal, short columnar cells.. Make fluid transporting epithelium -Typical pop of cells that have highly infolded lateral basal membrane to them.. Sit on conn tissue that’s highly vascular |
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where is perilymph in Cochlea?
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scala vestibuli
scala tympani |
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what does perilymph in Cochlea come from?
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made by periosteum
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what's the helicotremma?
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-opening @ cochlea apex
-conn scala vestibuili + scala tympani |
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where is organ of Corti?
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on basilar membrane that spans b/w spiral lamina and spiral ligament
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describe vestibular membrane:
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thin; has conn tissue core; made of simple squamous epithelial cells
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what window does Scala vestibuli communicate with?
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the oval window
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what window does Scala tympani communicate with?
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the round window
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what fluid bathes organ of Corti?
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endolymph made by stria vascularis
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what are the 2 main parts of the organ of Corti?
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-neuroepithelial auditory hair cells
-tectorial membrane |
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what makes up the neuroepithelial auditory hair cells of the organ of Corti?
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1 row inner hair cells
3-4 rows of outer hair cells "hairs" = stereocilia |
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how do stereocilia interact w/ tectorial membrane in organ of Corti?
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stereocilia of hair cells touch the tectorial membrane, but are not embedded in it
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what's the tectorial membrane of the organ of Corti secreted by?
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secreted by tall columnar cells on medial side that sit above bony spiral lamina/limbus
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what happens when interaction b/w outer and inner hair cells of stereocilia and tectorial membrane?
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triggers neuroanatomical impulse that is integrated at higher centers for sense of hearing
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how is sound perceived?
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transmission of sound wave through scala vestibuli & tympani
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compression soundwave hits.. and ....
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displaces tympanic membrane.. Tympanic membrane has motion that’s transmitted thru middle ear to this oval window by ossicles.. Displaces oval window (ossicles transport force to oval window)
All of compartment is filled w/ fluid (incompressible).. bony labyrinth of Cochlea is not going to give way.. Round window bulges toward middle ear to relieve pressure , which gives opportunity for mvmnt of basilar membrane . Wave is then transmitted thru scala vestibuli past helicotrema and into scala tympani .. During process of mvmnt of wave action, basilar membrane is displaced |
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the movement of ___________ affects the interaction b/w special sensory cells:
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the mvmnt of the basilar membrane that affects interaction b/w special sensory cells, inner hair cells, outer hair cells of organ of corti and their interaction w/ tectorial membrane
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what's the relationship b/w basilar membrane and tectorial membrane?
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Tectorial membrane is hinged medially and basilar membrane is hinged/has pivot pt laterally
So displacement of basilar membrane and displacement of tectorial membrane is independent of one another… can have interaction that makes shear forces on stereocilia that are reaching up to touch tectorial membrane |
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compare/contrast vestibular hair cells and auditory hair cells of organ of corti:
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struc diff
same concept of stimulus auditory- no kinocilium vestibular hair cells- kinocilium |
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what happens when there's stereocilia movement of vestibular hair cell?
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mvmnt open K+ channels.. Flow of those ions depolarizes cell and signals/allows Ca2+ influx into cell.. Ca2+ influx into cell triggers neurotransmitter release at synapse w/ central conn.. That signal processed centrally
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the basilar membrane is narrow and tense @ the
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base of the cochlea
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high pitch sounds:
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displace the basilar membrane at the base
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low pitch sounds:
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localize toward the apex of the cochlea
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what happens when basilar membrane and tectorial membrane moves?
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causes displacement at interface in interaction of stereocilia and bottom side of tectorial membrane… that interaction shows tonotopic localization along length of cochlea… the width of the basilar membrane is diff at base than it is at the apex
At the base, it’s more narrow than it is at apex |
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high frequency sounds displace:
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hair cells in tectorial membrane at base of cochlea at base more readily than they do at apex
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Low pitch sounds are the interaction b/w:
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tectorial membrane and hair cells at apex
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tonotopic localization of sound!
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basilar membrane is narrow and tense at the base of the cochlea.
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what's the vestibular apparatus?
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system of neuroepithelial bodies associated with the semicircular canals, the utricle and the saccule
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what's the vestibular apparatus responsible for?
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-rotational mvmnt and acceleration
-position of head in space relative to gravity |
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what's the vestibular apparatus a component of?
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-component of membranous labyrinth
-continous w/ scala media -filled w/ endolymph |
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what's the purpose of the semicircular canals?
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to sense rotational mvmnt
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describe semicircular canals:
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-positioned @ 90 degrees to one another
-sensory elements w/i dilated ampulae -Crista ampularis -cupula/cupola |
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what's the Crista ampularis?
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-sensory unit of semicircular canals
-sensory hair cells atop conn tissue ridge |
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what's cupula/cupola?
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-part of semicircular canals
-gelatinous mass spans width of semicircular canal -degree of deflection and rapidity of deflection sends signals to underlying endothelium that’s sent centrally for processing --> stimulates impulses |
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what's the purpose of the utricle and saccule?
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senses gravity dependent movement
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what's the macula?
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sensory unit of utricle and saccule
-Has special sensory cells w/ long stereocilia that extend into gelatinous matrix In macula, there are calcium carbonate crystals embedded in gelatinous matrix.. Impart weight/mass to this and constantly stimulate hair cells |
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how does utricle and saccule sense gravity dependent movement?
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Weight of otoliths acts to stimulate hair cells, thus the maculae sense gravity and changes of position relative to gravity.
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how's mvmnt of head relative to gravity sensed?
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sensed by change in how much pressure is placed on surface of stereocilia from this overlying gelatinous layer that sits on top.. Weight of ossicle of otoliths acts to stimulate these hair cells to help them sense position of head in space
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what can lead to nausea?
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vibration of gelatinous membrane
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what's the otolithic membrane?
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otoliths + gelatinous membrane
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what happens when sound waves are transmitted to inner ear?
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there’s motion of basilar membrane that’s somewhat independent of motion of tectorial membrane, allowing displacement and interaction b/w tectorial membrane and outer hair cells and stimulating synapses b/w sensory cells and neurons they interact w/
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