Vestibular System

Question 1

What are the five components of the vestibular system

Answer 1

peripheral receptor apparatus
Central vestibular nuclei
Vestibuloocular Network
Vestibulospinal Network
Vestibulothalamocortical Network

Question 2

Characteristics of perilymph

Where is it found?

Answer 2

Less K+, more Na+
Bathes vestibular portion of CN VIII

Bony labyrinth

Question 3

Characteristics of endolymph

Where is it found?

Answer 3

More K+, less Na+
Directly interacts with vestibular and cochlear cells

Membranous Labyrinth

Question 4

Role of semicircular canals

How many are there?

Answer 4

Detect rotational movements

Anterior, Posterior, Horizontal

Question 5

Role of Otolith Organs

How many are there?

Answer 5

Detect linear movements

Utricle, Saccule

Question 6

What innervates the vestibular receptor organs

What gives blood supply to them?

Answer 6

Primary afferent fibers of vestibular ganglion

Labryinthine A. (Branch off AICA), and Stylomastoid A.

Question 7

What connects the saccula to the cochlea?

Answer 7

Ductus Reuniens

Question 8

Cause of Meniere’s Disease

Answer 8

Improper ion balance between perilymph and endolymph

Results in abnormal endolymph volume

Question 9

Sx of Meniere’s Disease

Answer 9

Vertigo
Nystagmus
Nausea
Fluctuating hearing loss

Question 10

Type I Hair cells

Answer 10

chalice shaped, surrounded by afferent terminal (nerve calyx)

Shorter than Type II

Question 11

Type II Hair cells

Answer 11

longer

Cylindrical shaped

Question 12

Steps that occur after rotational head movement occurs

Answer 12

Rotational Head movement
Angular acceleration
Endolymphe displaced
Cupula is moved to one side or another
Stereocilia is displaced in same direction as cupula

Towards kinocilium = depolarization of hair cell
Away from kinocilium = hyperpolarization of hair cell

Question 13

Where is the superior vestibular nucleus found?

Answer 13

Supero-lateral in the central pons

Bordered by restiform body and 4th ventricle

Question 14

Where is the medial vestibular nucleus found?

Answer 14

Lateral floor of 4th ventricle

Question 15

Where is the lateral vestibular nucleus found?

Answer 15

Lateral to medial vestibular cells

*Contains Deiters cells (large neurons)

Question 16

Where is the inferior vestibular nucleus

Answer 16

Extends through medulla, lateral to medial vestibular

Question 17

What fibers travel through the juxtarestiform body?

Answer 17

Primary vestibulocerebellar Fibers

Question 18

What vestibular receptors are used in vertical movements for the vestibuloocular reflex?

Answer 18

Vertical semicircular canals and saccule

Question 19

What vestibular receptors are used in horizontal movements for the vestibuloocular reflex?

Answer 19

Horizontal semicircular canals and utricle

Question 20

What vestibular receptors are used in torsional movements for the vestibuloocular reflex?

Answer 20

Vertical semicircular canal and utricle

Question 21

During the Vestibuloocular reflex, what fibers are stopped from producing inhibitory signals on the IL abducens nucleus?

Answer 21

CL Commissural fibers

Question 22

Caloric test

Answer 22

Put water in ear, should produce nystagmus
Cold water = Opposite side nystagmus
Warm water = Same side nystagmus

Question 23

Positive Caloric Test

Answer 23

No nystagmus is produced IL

Question 24

Fxn of the Vestibulospinal Network

Answer 24

influence muscle tone and reflexive postural adjustments

Question 25

What areas of the vestibular cortex make up the primary somatosensory cortex

Answer 25

Areas 2v and 3a

Whole body motion

Question 26

Area 7

Answer 26

parietal cortex

spatial/visual motion

Question 27

Insular area of lateral sulcus, PIVC

Answer 27

Respond to body motion, proprioception, motion stimuli

Question 28

Prefrontal cortex; superior frontal gyrus

Answer 28

Related to frontal eye fields

Control of saccades and smooth pursuit eye movements