auditory and vestibular system Flashcards
1
Q
auditory and vestibular receptors are located in what part of the temporal bone
A
petrous part
2
Q
what is located within the vesituble
A
utricle and saccule
3
Q
the semicircular canals house the
A
semicircular ducts
4
Q
perilymph
A
fluid filling space outside the membranes labrinyth. fills perilymphatic space between bony an membranous labyrinth. continuous with subarachnoid space
5
Q
perilymph is similar to
A
extracellular fluid because it contains lots of Na
6
Q
endolymph
A
fills membranous labyrinth. continuous through and closed system
7
Q
endolymph is similar to
A
intracellular fluid
8
Q
cells within the walls of the membranous labyrinth are connected via ___ and create a ____
A
tight junctions, diffusion barrier
9
Q
stria vasculararis
A
cells within the cochlea that secrete endolymph
10
Q
where is the endolymph reabsorbed
A
endolymphatic sac that is embedded in dura matter of temporal bone
11
Q
hair cells are
A
auditory and vestibular receptors
12
Q
what part of the hair cell projects into the endolymph
A
sterocilia (more like microvilli with actin corse and cross linked)
13
Q
basal surface of hair cells synapse on what nerve
A
CN 8. which goes to the CNS
14
Q
tallest sterocilia
A
kinocilium; found in vestibular portion
15
Q
the tallest sterocilia projects into the
A
gelatinous mass
16
Q
hair cells are ____ and channels
A
mechanosensitive and transduction channels (turn mechanical energy into electrical signal)
17
Q
tip links
A
connect sterocilia
18
Q
how are hair cells depolarized
A
deflect towards tallest sterocilia which stretches the tip links and fires off VIII fibers
19
Q
differences in the physical arrangement of hair cells determines what
A
the stimuli to which they are most sensitive
20
Q
parts that use the same general mechanisms
A
cochlea, vestibule, semicircular canals
21
Q
head movement
A
semicircular ducts
22
Q
head position
A
utricle and saccule
23
Q
sound
A
cochlea
24
Q
outer and middle ear are ____ while the inner ear is ____
A
air filled, liquid filled
25
pathway of sound
auricle, external auditory meatus, tympanic membrane, middle ear, ossicles (Malleus, incus, and stapes), oval window, vestibule, cochlea
26
cochlea bone forms
2 3/4 turns
27
cochlear duct is what shape in cross sections
triangular
28
core of spongy bone inside the middle of the cochlea
modulus with osseous serial lamina
29
threads of the "screw" or modiolus
osseous spiral lamina
30
the basilar membrane connects...?
the osseous spiral lamina to the temporal bone
31
helicotrema
hole in the coil of the cochlea
32
traveling waves in the basilar membrane stimulate ___ in the _____
hair cells, organ of court (location depends of sound frequency)
33
intensity of sound is determined by
the rate and number of nerves firing
34
the frequency of sound is determined by
the basilar membrane and the organ of court (tonotopic organization)
35
the location of sound is accomplished by
comparing stimuli between ears within the CNS (superior olivary nucleus)
36
where do hair cells sit
on the basilar membrane
37
inner hair cells do not plug into the ____ while outer hair cells do plug into the ____
tectorial membrane
38
stiff at the base (responds to high frequencies) and floppy at the apex (low frequencies)
basilar membrane
39
the organization maintained in the CNS
tonotopic organization
40
cochlear implants only work when
hair cells are damaged but the CN 8 nerve endings are still intact
41
cochlear implants are placed into
the round window into the scala tympani and different points along the basilar membrane
42
spiral ganglion
contains the primary afferent cell bodies stimulated by hair cells
43
where do the primary afferents (stimulated by hair cells) synapse
both the dorsal cochlear nucleus and the ventral cochlear nuclleus
44
the dorsal cochlear nucleus and ventral cochlear nucleus project
bilaterally
45
where do the second order fibers from the dorsal cochlear nucleus ascend in
the lateral lemniscus
46
second order fibers from the ventral cochlear nucleus synapse at the
superior olivary nucleus (involved in sound localization)
47
the ventral cochlear nucleus
synapses in the superior olivary nucleus by crossing thru the TRAPEZOID BODY then the fibers ascend thru the lateral lemniscus
48
where does the lateral lemniscus terminate
at the inferior colliculus (in midbrain)
49
where does the inferior colliculus send fibers to
thru the inferior brachium to the medial geniculate nucleus (MGN) of the thalamus
50
where does the medial geniculate nucleus (MGN) project to
transverse temporal gyro which is the primary auditory cortex. (superior aspect of temporal lobe)
51
main functions of vestibular system
regulate posture (erector spinal muscles), coordinate eye movement, coordinate head moements
52
what are the bony portion son the vestibular division
1vestibule and 3 semicircular canals
53
what are the membranous portions of the vestibular division
2 otolithic organs (saccule and utricle) and 3 semicircular ducts (anterior, posterior and horizontal)
54
ampulla
dilation in each semicircular duct
55
structures of the ampulla
1. crista (similar to organ of court): supporting cells and hair cells
2. Cupula (gelatinous mass)
56
functions of the cupula
a gelatinous mass that creates a partition across the ampulla. it responds to ANGULAR ACCELERATION (when you turn). 3 ducts are arranged so rotation can be detected from 3d plane
57
are the semicircular ducts able to detect continuous rotation
no. in the beginning of rotation the endolymph stays behind, then rotation is maintained and the dnolymph catches up. once rotation stops the endolymph keeps going. this is not found in nature more for rollercoasters
58
macula
the hair cells in the utricle and saccule
59
otolithic membrane
the gelatinous mass that sterocilia project into in the vestibular system
60
what flops in response to various positions of the head to indication head position to linear accelerations
otolithic membrane
61
utricle is responsible for
forward/ backward nd side to side motions of the head when moving in a straight line
62
saccule is responsible for
forward/backward and up and down motion son the head when moving in a straight line
63
each head position has a ____ of stimulation
unique pattern
64
what causes vertigo
when otoconia rocks that are sensitive to gravity float into the semicircular duct
65
hair cells stimulate the ______
peripheral process of the vestibular division of CN 8
66
the vestibular ganglion projects directly into the?
cerebellum and vestibular nuclei
67
juxtarestiform body
how the vestibular ganglion projects directly into the cerebellum part of the INFERIOR CEREBELLAR PEDUNCLE
68
what are the 4 vestibular nuclei within the vestibular nuclear complex on each side
inferior, medial, lateral, and superior
69
otoconia
small bits of calcium carbonate in the oolitic membrane called ear sand
70
projections from the ipsilateral vestibular ganglion go to which 4 areas
1. cerebellum
2. spinal cord
3. visual information nuclei
4. contralateral vestibular nuclei (extensively interconnected)
71
projections from the ipsilater vestibular ganglion reach the cerebellum via
the flocculondular lobe. this coordinates head movement
72
projections from the ipsilater vestibular ganglion reach the spinal cord via
spinovestibular fibers. this regulates posture
73
projections from the ipsilater vestibular ganglion go to the visual information nuclei in the brainstem in order to?
distinguish movement and just movement across the retina
74
projections out of the vestibular nuclei to CN III, IV, and VI does what?
coordinates eye movement
75
contralateral projections out of the vestibular nuclei to the thalamus does what?
conscious awareness
76
projections out of the vestibular nuclei to the visceral nuclei does what
autonomic effects (seasickness)
77
functions the the lateral vestibulospinal tract
stabilizes posture
78
lateral vestibulospinal tract orientation
stays ipsilateral
79
course of the lateral vestibulospinal tract
lateral vestibular nucleus---- runs next to the spinothalamic tract---- antigravity muscles at all spinal levels
80
functions of the medial vestibulospinal tract
stabilize head from waling and eye movements
81
orientation of the medial vestibulospinal tract
bilateral
82
course of the medial vestibulospinal tract
median vestibular nucleus ---- MLF---- cervical spinal cord
83
function of vestibuloocular reflex
generate eye movements that compensate for head movements (keeps eye fixed on object in visual field)
(Still works in the dark but different than tracking)
84
pathway of the vestibuloocular reflex
semicircular canals ---vestibular nuclei --- MLF and RF ---- nuclei of CN III, 4 and 6
85
afferent limb of vestibuloocular reflex
CN 8
86
efferent limb of vestibuloocular reflex
nuclei that control the extra ocular muscles
87
interneuronal connects in vestibuloocular reflex
MLF and RF
88
nystagmus
physiological: aid in keeping images on retina during movement (reset movement)
pathological: astagmus shaking of eye but doesn't change object fixed on or eyes shakeng all the time and doesn't change visual field
89
cupula and gravity and what can affect this relationship
normal: cupula has same density as endolymph so not deflected by gravity
affected by: alcohol consumption which penetrates inner ear or dislodged otoconia "plunger effect"
90
what sense work together to help with balance (position sense)
vestibular sense, proprioceptive sense and visual sense. 2 out of 3 functions must be working
91
rhombergs sign
loss of 2 or 3 senses is disabling for balance
