vestibular system Flashcards

1
Q

what are responsible for angular motions?

A

semicircular canals

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2
Q

what is responsible for linear motion?

A

vestibule

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3
Q

what is perilymph?

A

CSF and is high and Na
this is outside of membrane
sits between the bone and the membrane

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4
Q

what is endolymph?

A

fluid that is high in K

this is inside of membranes

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5
Q

what are the three semicircular canals?

A

superior
posterior
horizontal

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6
Q

what motion would the superior semicircular canal detect?

A

a nod for yes (up and down)

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7
Q

what motion would the posterior semicircular canal detect?

A

head tilt left or right (ear towards shoulder)

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8
Q

what motion would the horizontal semicircular canal detect?

A

shaking head no ( left and right axial rotation)

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9
Q

how do the semicircular canals overcome inertia?

A

the cupula is a sack that covers the hair cells. The sack is full of endolymph

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10
Q

what are the organs that make up the vestibular system?

A

utricle and saccule
(otolithic organs)
these sense linear motion
gravity

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11
Q

what are otoconia?

A

calcium crystals, these move with gravity. as you go up the move up and as you go down they hit the hair cells.

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12
Q

what is the striola?

A

the bag that holds the otoconia

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13
Q

what is the otolith membrane?

A

the sack to covers the hair cells and is what moves the hair cells depending on the movement

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14
Q

what does multimodal convergence mean?

A

immediate integration with other sensory inputs

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15
Q

where is the central vestibular nucleus located?

A

pons/medulla

dorsal portions

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16
Q

what are the four major central vestibular nuclei?

A

superior(all in the pons) lateral, medial, and inferior vestibular nuclei

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17
Q

with cilium how are the potassium channels open?

A

stretch activated

depending on the direction of bend, it will either activate or slow down the signal

18
Q

in the utricle and saccule how are the hair cells aligned?

A

in opposite directions

19
Q

where are the hair cells located in the semicircular canals?

A

in the ampulla of each canal

20
Q

what does the horizontal canal do?

A

adjusts your eyes based on head movement via the superior vestibular nucleus

21
Q

Vestibulo-cerebellar network

superior vestibular nucleus

A

-impulse directly from the semi circular canals that goes to the cerebellum.
-coordination of:
posture
balance
eye movements (saccade control) fast movements of the eyes.

22
Q

Vestibulo-ocular network

A
  • horizontal canal to the superior vestibular nucleus.
  • horizontal eye movement.
  • *control is in the pons**
23
Q

what is nystagmus?

A

eyes drift/jerk to the opposite side of head movement first(slow) and then quickly jerk to the side of motion.

24
Q

pathway from the horizontal canal to the muscles?

A

vestibular nucleus (superior, pons) to the abducens nucleus (pons) and then to the contralateral lateral rectus and oculomotor (along the medial longitudinal fasiculus)

25
how do you test the vestibular function?
caloric vestibular stimulation (CVS) galvanic vestibular stimulation (GVS) sound-induced vestibular stimulation
26
Vestibulo-ocular | caloric nystagmus test
- subject tilts head back to make horizontal canal vertical - ear is irrigated with either warm or cold water - nystagmus is the result
27
example of caloric nystagmus with warm water in the right ear **tests for intact pons
endolymph expands(rises) causing motion towards the utricle -slow phase: eyes left initially -fast phase: corrective saccade to the right cold water will do the opposite. **whatever side the warm water is put in is the side of the fast saccade**
28
what does COWS mean in terms of caloric nystagmus?
``` C cold opposite O opposite W warm S same **reference to fast response** ```
29
caloric nystagmus signs | slow phase absent
horizontal canal weakness (ipsilateral) | damage to the MLF/pons
30
caloric nystagmus signs | fast phase absent
cerebral damage
31
caloric nystagmus signs | both phases lost
bilateral hindbrain | very poor prognosis
32
vestibulo-thalamo-cortical
vestibular nuclei(superior, lateral, and inferior) of the pons and medulla to the thalamus to the cortex - top down control - mostly angular motion with some utricle saccule (linear) * *only thalamic relay
33
vestibulo-spinal | lateral and medial vestibulospinal tracts
response to linear motion (utricle and saccule) | in the medulla
34
the lateral vestiubulospinal tract interacts with what? | excitatory or inhibitory
the alpha motor neurons | excitatory output of upper limbs, head, neck, back, and legs
35
the medial vestibulospinal tracts interacts with what? | excitatory or inhibitory
alpha motor neurons but is inhibitory for the most part. | inhibitory output to neck and back
36
what is subjective vertigo?
the person feels as if they are spinning | -vestibular system injury
37
what is objective vertigo?
the room is spinning | -central vestibular issues
38
what do the medial and lateral vestibulospinal tract travel in?
the medial longitudinal fasiculus (MLF)
39
vestibular signs and symptoms
balance: steadiness, symmetry, dynamic stability, gait deficiencies dizziness: lightheadedness, unsteadiness, giddiness, faintness, mental confusion, **imprecise
40
what is an acoustic neuroma (shwannoma)?
benign tumor that produces pressure on CN VIII | symptoms: unilateral nystagmus, vertigo, tinnitus, hearing loss.