W03_07 Motor Control 4: Vestibular System

Question 1

what reflex keep the eyes fixed during head movements?

Answer 1

vestibulo-ocular reflex

Question 2

what reflex keeps the head balanced during body movements?

Answer 2

vestibulo-colic reflex

Question 3

what kind of organs are the utricle and saccule?

Answer 3

otolith organs

Question 4

saccule detects motion in which plane?

Answer 4

vertical

Question 5

utricle detects motion in which plane?

Answer 5

horizontal

Question 6

what is the fluid in the semicircular canals called?

Answer 6

endolymph

Question 7

what do you call the tallest sensory hair cells in the vestibular apparatus?

Answer 7

kinocillium

Question 8

how does the receptor in the semicircular canals work?

Answer 8

endolymph beats against a membrane called a cupula. this is linked to hair cells, whose directional movement directs their neuronal action.

Question 9

how does the receptor of the otolith organs work?

Answer 9

endolymph moves otoconia (gravel) embedded in a gelatinous membrane. otoconia stimulate the hair cells and kinocillium to direct their neuronal action.

Question 10

what is the name of the receptor in the semicircular canals?

Answer 10

cristae ampullaris

Question 11

function of the vestibule and otolith?

Answer 11

linear acceleration perception
body position
eye position

Question 12

hair cells bending towards kinocillium results in?

Answer 12

depolarization and rapid firing

Question 13

hair cells bending away from kinocillium results in?

Answer 13

hyperpolarization and decreased firing

Question 14

how does head left rotation affect the neuronal pathway?

Answer 14

vestibular nerve to
vestibulocochlear nerve to
vestibular nucleus to
contralateral abducens nucleus and ipsilateral oculomotor nucleus. 
eyes are pulled to look to the right.

Question 15

what is the name of the tract that connects the vestibular nuclei to the III, IV, and VI nuclei?

Answer 15

medial logitudinal fasciculus

Question 16

what is the gain of the VOR? what can modify the gain?

Answer 16

gain = 1. cerebellum can modify the gain.

Question 17

what is nystagmus?

Answer 17

repetitive movement of eyes back and forth. can be jerky or pendular.

Question 18

what is vertigo?

Answer 18

feeling of motion when stationary

Question 19

what are some causes of nystagmus?

Answer 19

diseases of retina, labyrinth (meniere’s), VIII, cerebellum, brainstem, toxicity

Question 20

which group of muscles does the vestibulospinal system favour? (think function of vestibulo-)

Answer 20

extensors, to help us maintain balance and stay upright against gravity.

Question 21

which reflexes help us maintain stable heads during movement?

Answer 21

vestibulo-colic reflex

Question 22

the medial longitudinal fasciculus is connected to which tract of the spinal cord?

Answer 22

medial vestibulospinal tract