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Block 12 Hearing

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klau253's version from 2017-05-28 21:44

Section

Outer ear
Question Answer
componentsauricle, ext auditory meatus, eardrum
fxnconverts acoustic energy to kinetic energy
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Mid Ear
Question Answer
Componentsossicles to oval window, eustachian tube
Fxnconverts kinetic to hydraulic
Ossiclesmalleus, incus, stapes
Eustachian tubefrom mid ear to nasopharynx, allows pressure equalisation between mid ear and external ear
Tegmen tympanimuscle of malleus, innervated by Trigeminal V3
Stapediusmuscle to stapes, innervated by stapedial nerve (branch from CN VII)
chorda tympani nervebranch of CN VII, ant. 2/3 tongue taste
Acoustic reflexboth tegmen tympani and stapedius contract in response to high intensity sound
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Inner Ear
Question Answer
componentsvestibular sys and cochlear
Fxnconverts kinetic to hydraulic, then to electrochemical signal via CN VIII
Bony labyrinthpetrous part of temporal bone
Membranous labyrinthfilled with endolymph (K+)
perilymphNa+, separates bony and membranous
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Cochlea
Question Answer
Scala mediafilled with endolymph
Scala vestibuli and tympaniperilymph
Reissner membraneseparates vestibuli and media
Basilar membraneseapartes media and tympani
Organ of cortisensory epithelium on basilar membrane
Tonotopyhigh-pitch sound sensed at base of cochlear
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Auditory pathway
Question Answer
SLIMsup. olivary complex --> lateral lemniscus --> inf. colliculus --> medial geniculate nucleus
Decussationbetween cochlear nuclei and sup. olivary, inf. colliculi
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Hearing loss
Conductive hearing loss
Question Answer
Problemfrom outer ear to middle ear
Causesear wax, otitis externa/media, perforated ear drum, membrane tension
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Sensorineural hearing loss
Question Answer
Probleminner ear to auditory cortex
Causescongenital, ototoxic drugs, age, measles, mumps, meningitis, physical trauma, noise-induced
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Rinnie test
Question Answer
Normal ear/sensorineural lossBC>AC
ConductiveAC>BC
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Weber test
Question Answer
if normal ear hears loudersensorineural
if defective ear hears louderconductive
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