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35 Cards in this Set
- Front
- Back
pinna/auricle
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-outer portion of ear
-collects sound |
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external auditory meatus (EAM)
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-funnels sound into tympanic membrane
-S-shaped -more constricted at area of bone & cartilage as sound is localized |
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frequencies most enhanced by outer ear
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1500-1800 Hz
|
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tympanic membrane (TM)
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-eardrum
-boundary between outer and middle ear |
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ossicles
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-maleus
-incus -stapes -used for impedance matching |
|
oval window
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entry to the cochlea
|
|
impedance
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-the way your eardrum is going to move
-P=F/A -increase F & P ==> decrease A |
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three types of impedance matching mechanisms
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-lever difference: 2 dB
-buckling difference: 4-6 dB -area difference: 25 dB |
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lever difference
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-2 dB
-traveling through ossicular chain ==> amplification -small force applied to lever of incus (mabubrium) ==> large force on long arm of lever |
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buckling difference
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-4-6 dB
-how eardrum changes its shape in response to different frequencis |
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area difference
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-25 dB
-area difference between TM and oval window -going from big, localizing to small area |
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effective area of tympanic membrane
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55mm sq.
|
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effective area of oval window
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3.2 mm sq.
|
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acoustical gain to the area
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17:1
associated with 25 dB |
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dB of gain in middle ear lever
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2 dB
|
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tonotopic
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-high frequencies perceived at one end, high frequencies perceived at other end
|
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basilar membrane
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-base: smaller, stiffer, thinner, lighter
-apex: bigger, less stiff, thicker, heavier |
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auditory pathway
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cochlear nucleus ==> superior olivary complex ==> inferior colliculus ==> medial geniculate body ==> temporal lobe
|
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tympanic muscles
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-muscles of middle ear attached to ossicles
-protect middle ear from damage -stapedius -tensor tympani |
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eustachian tube
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-entryway into pharynx
-purpose: ventilation -inferior border of middle ear |
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which cranial nerve is the stapedius associated with?
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VII Cranial Nerve: Facial Nerve
|
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vastibular system
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accelorometer in temporal bone, important for balance
|
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round window
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separates middle ear and scala tympani
|
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two portions of cochlea
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-osseous portion
-membranous portion - embedded within osseous portion |
|
osseous portion of cochlea
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-bony portion
-divided into two chambers by spiral lamina -core of bony portion: modiolus |
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liquid associated with membranous structures
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endolymph
|
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liquid associated with bony structures
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perilymph
|
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helicotrema
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region in inner ear where scala vestibuli and scala tympani communicate
|
|
outer hair cells
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13,500
three rows |
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inner hair cells
|
3,500
one row |
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tectoral membrane
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-contains outer hair cells
-fibrogelatenous |
|
cochlear nuclus
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-first stop in auditory pathway
-processes ipsilateral information -deals with timing and loudness |
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joint between malleus and incus
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malleoincudal joint
|
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joint between incus and stapes
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incudostapedial joint
|
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% of auditory nerve fibers devoted to outer vs. inner hair cells
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-outer hair cells: 5%
-inner hair cells: 95% |