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34 Cards in this Set
- Front
- Back
What are the routes of sound conduction to the inner ear?
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air and bone
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What is the function of the middle ear?
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amplify pressure oscillation during transmission from air to liquid
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What is the acousitc stapedius reflex?
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a loud sound causes a large discharge of the cochlear n which acitvites vent cochlear nucleus, sup olive, facial n. which causes tensing of stapedius muscle
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Where is endolymph?
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in membraneous labyrinth
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Where is perilymph?
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within the two scalae
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What produces endolymph?
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stria vascularis
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What produces perilymph?
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periosteal lining
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What is the composition of endolymph?
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low protein and Na, High K
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What is the composition of the perilymph?
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NaCl, low protein
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How are varoius frequencies separated?
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Low-helicotrema, high-near windows
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What is the modiolus?
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The bone surrounding the bony labyrinth
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Where does the scala tympani run?
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round window to helicotrema
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Where does the scala vestibule run?
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helicotrema to oval window. it is continuous with the bony vestibular labyrinth
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What are the parts of the membranous labyrinth?
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cochlear duct and organ of corti
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What connects the membranous labyrinth together?
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ductus reunions
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What does the endolymph flow thru?
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the endolymphatic sac and the endolymphatic duct
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How many inner row?
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1
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How many outer row?
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3
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Hear cells receive inhibitory input from what?
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the olivocochlear nerve fibers
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What is the mem pot gradient between the endolymph and the hair cell?
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150mV
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What opens the siral ligaments mecahnosensitive K channels?
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movement of cilia towards the spiral ligament
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What happens when K channels open?
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depols, triggering Ca entry and NT release of Glut which activates cochlear nerve fibers
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What is the trap door theory?
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Movement of stereocilia away from the spiral ligament hyperpols the cell, but an intermediate position leads to a reduced level of K to maintain resting potential
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What is the function of outer cells?
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amplification of cilia movements
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What forms the trapezoid body?
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ventral cochlear nucleus projects to the ipsilateral and contralateral
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Where does the dorsal cochlear nucleus project?
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contralateral lemniscus terminating in lat lemniscus
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What is the Rinne's Test?
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mastoid process then lateral to ear, which is louder
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What if bone conduction is louder is louder in Rinne Test?
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conductive deafness
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What if Webber test is louder in one ear?
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conductive deafness in that ear
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What is conduction deafness?
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dec vibration of basilar membreane, dec air conduction, low frequencies
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What causes conduction deafness?
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foreign obejcts, infection
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What is sensorineural deafness?
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loss of both air and bone, high frequencies caused by haircell damage
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What is neural deafness?
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unilateral hearing loss because of leasion to auditory nerve
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What is central deafness?
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lesion to CNS
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