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Anatomy II > Lecture 29: Neuroanatomy of the Auditory and Vestibular Systems > Flashcards

Lecture 29: Neuroanatomy of the Auditory and Vestibular Systems Flashcards

1
Q

3 functions of vestibular system

A

transduce and interpret head movements
maintain position of visual axes when head is moving = vestibulo-ocular reflex
send motor commands to trunk and limb muscles in order to maintain balance

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2
Q

vestibulo ocular reflex

A

when head is moving but eyes can still look at target

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3
Q

where are vestibular nuclei located

A

brainstem

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4
Q

vestibular nuclei receive info from (2)

A

info on head movement from organs of balance
muscle firing from cerebellum

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5
Q

which region of brainstem coordinates motor output through cortical and vestibular pathways

A

cerebellum

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6
Q

cerebellum receives info from what 3 regions

A

cortex
spinal cord
vestibular system

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7
Q

lesions to CN VIII or vestibular nuclei lead to disruptions in (4)

A

stance
head posture
balance
loss of extensor muscle tone

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8
Q

bony labyrinth: location, definition, what is contained (general)

A

bony outer shell of deeper membranous labyrinth
within petrous portion of temporal bone
encases inner ear
organs of balance and hearing = vestibular and cochlear organs

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9
Q

what are the vestibular organs (4)

A

semicircular ducts
utricle
saccule
vestibular nerve

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10
Q

what are the cochlear organs (2)

A

cochlear duct
cochlear nerve

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11
Q

membranous labyrinth contains

A

endolymph

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12
Q

region between membranous ducts and walls of bony labyrinth contain

A

perilymph

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13
Q

endolymph vs perilymph

A

endolymph = more [K+]
perilymph = more [Na+]

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14
Q

vestibular and cochlear apparatuses rely on what

A

mechanical displacement of mechanoreceptors by fluid (lymph derivative)

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15
Q

definition of acceleration

A

rate of change of velocity / time

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16
Q

utricle: definition, function

A

vestibular organ
monitor and activate response to linear acceleration of horizontal movements relative to gravity (side to side)

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17
Q

saccule: definition, function

A

vestibular organ
monitor and activate response to linear acceleration of vertical movements relative to gravity (up and down)

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18
Q

3 semicircular ducts: definition, function

A

vestibular organ
respond to angular acceleration (rotation) of head in all planes = anterior, lateral and posterior semicircular canals

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19
Q

on each side of the head there are (6)

A

3 semicircular ducts each with 1 ampulla
1 utricle with 1 macula
1 saccula with 1 macula
1 vestibular ganglion

20
Q

ampulla =

A

dilation

21
Q

vestibular ganglion =

A

scarpa’s ganglion

22
Q

where are semicircular hair duct cells location

A

within ampulla

23
Q

effect of moving endolymph on cupula, stereocilia, kinocilium

A

bends capula
tilts stereocilia and kinocilium of hair cells

24
Q

semicircular duct hair cells general anatomy

A

cell body
stereocilia and kinocilium in contact with endolymph

25
Q

effect of displacement of specialized hair cells during movement (hint: changing membrane potentials)

A

opens mechanically gated K+ channel = depolarizes = more voltage gated Ca channels open = increases glutamate release

26
Q

depolarization vs hyperpolarization effect on channels

A

depolarization - more APs, open channels
hyperpolarization - less APs, close channels

27
Q

hair cells are located in which organs/areas (5)

A

semicircular duct
otolith organs = utricle, saccule
otolithic membrane
otoconia
macula

28
Q

otolith organ displacement process

A

moving head allows displacement of gelatinous cap –> cap moves and tilts stereocilia toward kinocilium –> hair cells depolarize = opens channels

29
Q

mirrored orientation of hair cells in macular organs

A

some hair cells depolarizing while others are hyperpolarizing
reversal line indicates this separation

30
Q

opposite polarity of hair cells: effect on firing rate, what side of head

A

depolarize on side of head toward which person is turning = increase firing rate of hair cells
hyperpolarize on side of head from which person is turning = decreased firing rate of hair cells

31
Q

relationship between magnitudes of firing rates in semicircular canals

A

should be equal
hyperpolarization = depolarization

32
Q

which nuclei compares the firing rates from each side

A

vestibular

33
Q

what must happen to redirect eyes when head rotates: vestibuloocular reflex (2)

A

motor commands to contract left lateral rectus muscle
motor commands to contract right medial rectus muscle

34
Q

lesions of vestibular portion of CN VIII, vestibular apparatus or vestibular nuclei

A

imbalance of APs received by vestibular nuclei
perception of moving when NOT

35
Q

function of auditory system

A

transduce and interpret vibrations due to sound

36
Q

which labyrinth contains sound transduction mechanism

A

cochlear

37
Q

position of cochlea relative to semicircular ducts

A

rostromedial

38
Q

sound transduction mechanism in cochlea

A

footplate of stapes transmits vibrations to membrane of oval window and perilymph of scala vestibuli

39
Q

fluid displacement from oval window creates

A

waves and displacements in membranes of cochlea

40
Q

scala vestibuli is filled with

A

perilymph

41
Q

what mechanism does hearing use for transduction

A

same as vestibular system = mechanoelectrical
stereocilia of hair cells are displaced

42
Q

neural sensation of hearing mechanism

A

displacement of tectorial and basilar membranes move stereocilia –> transduction of hair cell

43
Q

effect of varying material properties of basilar membrane

A

allows propagation of various waves in specific regions
sensitivities to certain frequencies in certain parts of basilar membranes –> brainstem nuclei

44
Q

interaural time differences used to compute location based on

A

timing differences between each side

45
Q

interaural level differences used to compute location based on

A

sound level differences received between each side (directionality)

46
Q

2 differences used to determine where sound came from

A

interaural time
interaural level

Anatomy II (36 decks)

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