vestibular system

Question 1

what are responsible for angular motions?

Answer 1

semicircular canals

Question 2

what is responsible for linear motion?

Answer 2

vestibule

Question 3

what is perilymph?

Answer 3

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

Question 4

what is endolymph?

Answer 4

fluid that is high in K

this is inside of membranes

Question 5

what are the three semicircular canals?

Answer 5

superior
posterior
horizontal

Question 6

what motion would the superior semicircular canal detect?

Answer 6

a nod for yes (up and down)

Question 7

what motion would the posterior semicircular canal detect?

Answer 7

head tilt left or right (ear towards shoulder)

Question 8

what motion would the horizontal semicircular canal detect?

Answer 8

shaking head no ( left and right axial rotation)

Question 9

how do the semicircular canals overcome inertia?

Answer 9

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

Question 10

what are the organs that make up the vestibular system?

Answer 10

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

Question 11

what are otoconia?

Answer 11

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

Question 12

what is the striola?

Answer 12

the bag that holds the otoconia

Question 13

what is the otolith membrane?

Answer 13

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

Question 14

what does multimodal convergence mean?

Answer 14

immediate integration with other sensory inputs

Question 15

where is the central vestibular nucleus located?

Answer 15

pons/medulla

dorsal portions

Question 16

what are the four major central vestibular nuclei?

Answer 16

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

Question 17

with cilium how are the potassium channels open?

Answer 17

stretch activated

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

Question 18

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

Answer 18

in opposite directions

Question 19

where are the hair cells located in the semicircular canals?

Answer 19

in the ampulla of each canal

Question 20

what does the horizontal canal do?

Answer 20

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

Question 21

Vestibulo-cerebellar network

superior vestibular nucleus

Answer 21

-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.

Question 22

Vestibulo-ocular network

Answer 22

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

Question 23

what is nystagmus?

Answer 23

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

Question 24

pathway from the horizontal canal to the muscles?

Answer 24

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

Question 25

how do you test the vestibular function?

Answer 25

caloric vestibular stimulation (CVS)
galvanic vestibular stimulation (GVS)
sound-induced vestibular stimulation

Question 26

Vestibulo-ocular

caloric nystagmus test

Answer 26

• subject tilts head back to make horizontal canal vertical
• ear is irrigated with either warm or cold water
• nystagmus is the result

Question 27

example of caloric nystagmus with warm water in the right ear
**tests for intact pons

Answer 27

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

Question 28

what does COWS mean in terms of caloric nystagmus?

Answer 28

C cold opposite
O opposite
W warm 
S same 
**reference to fast response**

Question 29

caloric nystagmus signs

slow phase absent

Answer 29

horizontal canal weakness (ipsilateral)

damage to the MLF/pons

Question 30

caloric nystagmus signs

fast phase absent

Answer 30

cerebral damage

Question 31

caloric nystagmus signs

both phases lost

Answer 31

bilateral hindbrain

very poor prognosis

Question 32

vestibulo-thalamo-cortical

Answer 32

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

Question 33

vestibulo-spinal

lateral and medial vestibulospinal tracts

Answer 33

response to linear motion (utricle and saccule)

in the medulla

Question 34

the lateral vestiubulospinal tract interacts with what?

excitatory or inhibitory

Answer 34

the alpha motor neurons

excitatory output of upper limbs, head, neck, back, and legs

Question 35

the medial vestibulospinal tracts interacts with what?

excitatory or inhibitory

Answer 35

alpha motor neurons but is inhibitory for the most part.

inhibitory output to neck and back

Question 36

what is subjective vertigo?

Answer 36

the person feels as if they are spinning

-vestibular system injury

Question 37

what is objective vertigo?

Answer 37

the room is spinning

-central vestibular issues

Question 38

what do the medial and lateral vestibulospinal tract travel in?

Answer 38

the medial longitudinal fasiculus (MLF)

Question 39

vestibular signs and symptoms

Answer 39

balance: steadiness, symmetry, dynamic stability, gait deficiencies
dizziness: lightheadedness, unsteadiness, giddiness, faintness, mental confusion, **imprecise

Question 40

what is an acoustic neuroma (shwannoma)?

Answer 40

benign tumor that produces pressure on CN VIII

symptoms: unilateral nystagmus, vertigo, tinnitus, hearing loss.