Auditory and Vestibular Systems I&II Flashcards

1
Q

what is amplitude (loudness) measured in?

A

decibels (dB)

-sensitivity is inconsistent

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2
Q

what is wavelength (frequency) measured in?

A

hertz (Hz)

  • normal range 20-20000 Hz
  • sensitive to 1000-3000 Hz to detect human voices
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3
Q

outer ear

A

pinna (funnel) and auditory tube (canal)

  • where foreign bodies are located
  • contain air
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4
Q

middle ear

A

amplifies sound; deep surface of tympanic membrane

  • malleus, incus, stapes
  • contain air
  • tensor tympani attaches to malleus - innervated by trigeminal (mandibular branch)
  • stapedius - facial nerve
  • limit vibratory capacity by contracting tensor tympani and stapedius
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5
Q

inner ear

A

contains cochlea - converts sound from air into liquid and contains afferent fibers

  • cells convert waves in liquid into electrical signals
  • higher frequencies –> narrow region near base
  • lower frequencies –> wider region near apex
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6
Q

organ of corti

A

contains inner and outer hair cells

-also supporting cells

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7
Q

role of kinocilium and stereocilia

A

project into endolymph turning wave signals into electrical signals

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8
Q

endolymphatic hydrops

A

too much perilymph

associated with Meniere’s disease

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9
Q

inner vs. outer hair cells

A

inner - perceive sound, high sensitivity

outer - amplify sound wave propagation, can be killed by prolonged ototoxic drugs/antibiotics –> hearing loss

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10
Q

otoacoustic emissions

A

sound travels from cochlea to auditory canal (reverse)

-tests auditory ability

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11
Q

ascending hearing pathway

A
  • inner hair cells –> spiral ganglion by CNVIII –> cochlear nuclei (1st synapse) –> superior olivary nucleus –> inferior colliculus (2nd synapse) –> auditory cortex
  • left and right auditory cortices ALWAYS receive input from BOTH ears
  • contralateral or ipsilateral fibers
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12
Q

auditory cortex frequencies

A
  • high frequency sounds - processed more medially, deeply

- low frequency sounds - processed more laterally, superficially

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13
Q

brodmanns areas

A
  • 41,42 = basic properties, detect thunder from gun shot

- 22 = pitch, intensity, emotion - pick up tone, sarcasm

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14
Q

descending hearing pathways

A
  • lateral olivocochlear efferents –> inner hair cells (go through spiral ganglion)
  • medial olivocochlear efferents –> outer hair cells (bypass spiral ganglion)
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15
Q

hearing reflex - ways to decrease volume

A
  • contract stapedius or tensor tympani –> dampen sustained loud noises
  • can also dampen with outer hair cells
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16
Q

hearing disorders

A
  1. hypoacusis = decreased hearing
  2. hyperacusis = increased hearing
  3. deafness = loss of hearing
  4. hallucinations
  5. neuroma
  6. tinnitus = hear sound with no sound present
17
Q

acoustic neuroma aka vestibular schwannoma

A

benign tumor on cranial nerve VIII

-tinnitus, loss of hearing, dizzy

18
Q

conductive hearing loss

A
  • outer ear - foreign body

- middle ear - dysfunction of auditory ossicles, fluid accumulation –> upper respiratory tract inflammation

19
Q

sensorineural hearing loss

A

dysfunction of hair cells

  • CNVIII works fine
  • treat with cochlear implants
20
Q

presbycusis

A

hearing loss due to aging

21
Q

where does sound/hearing occur?

A

cochlea

22
Q

where does balance occur?

A

saccule, utricle, cristae of semicircular ducts

23
Q

vestibule system

A
  • contains otolith organs - utricle and saccule
  • contain semicircular canal
  • suspended in perilymph - bony labyrinth
24
Q

what is affected by stapes induced pressure changes?

A

the cochlea, not the vestibular apparatus

25
Q

role of the cupulla w/I the ampulla

A

contains receptor and supporting cells

-rotation –> endolymph stagnant and displace semicircular canals –> deflect cupula and detracted by receptor cells

26
Q

semicircular duct

A

detect angular or rotational movement

27
Q

utricle

A

detect linear movement (side to side)

  • macula inferiorly
  • stereocilia superiorly
28
Q

saccule

A

detect linear movement (vertical)

  • macula medially
  • stereocilia laterally
29
Q

otoconia

A

in saccule and utricle

  • switch positions with linear movement
  • continued stimulation of hair cells in absence of semicircular duct (acceleration)
30
Q

ascending vestibular pathway

A

vestibular nuclei - input from accessory optic nuclei –> no change in gate if damaged

31
Q

descending vestibular pathway

A

vestibular nuclei transmit info to:

  • cranial nerves 3,4,6 –> extra ocular muscles
  • MVST –> CN11 –> head and upper body
  • LVST –> lower limbs
  • MLF –> connection b/w extra ocular muscles and MVST
32
Q

3 types of info. go to vestibular system

A
  • eyes, inner ears, proprioception
  • loss of 2 –> lose balance, dizzy, vertigo
  • overseen by cerebellum
33
Q

vestibulo-ocular reflex

A

turn head to left and eyes pull back toward right

  • ex. excitation increases contraction of right lateral rectus and left medial rectus
  • more affective than visual tracking
34
Q

damage to medial leminscal pathway vs. cerebellar damage

A

Romberg test

  • DML –> lose balance when closing eyes, loss of proprioception
  • cerebellar –> lose balance with eyes open
35
Q

nystagmus

A

normal - visual tracking

abnormal - vestibular dysfunction (CN8) –> dysfunctional tracking

36
Q

vertigo

A

positional hallucinations - loss of balance

-can be caused by acrophobia and can cause vestibular dysfunction

37
Q

benign paroxysmal positional vertigo

A

forceful head movement dislodges otoconia –> vertigo when head is in a certain position

38
Q

alcohol effects on vestibulocochlear system

A

infiltrates cupulae faster dropping density –> hair cells move quicker

  • spinning room (overly sensitive to movement)
  • rebound effect - alcohol leaves cupulae raising density and decreasing hair cell movement –> exaggerate movement
  • gate compromised
39
Q

alcohol effect on stapedius and tensor tympani muscles

A

reduces contraction of muscle increasing the sensitivity to sound (muscle tone relaxant)