Vestibular System

Question 1

What is the function of the vestibular system?

Answer 1

it reflexively controls the eye and body position in response to change in head position

Question 2

What do vestibular nuclei send information to?

Answer 2

medial longitudinal fasciculus and vestibulospinal tract

Question 3

Where does the medial longitudinal fasciculus send the information that it received from the vestibular nuclei to?

Answer 3

the motor nuclei of III, IV, and VI

Question 4

Where does the vestibulospinal tract send the information that it recieved from the vestibular nuclei to?

Answer 4

the skeletal muscles associated with eye and body position

Question 5

What type of neuron is the vestibular neuron?

Answer 5

a bipolar sensory neuron

Question 6

Where is the vestibular organ located?

Answer 6

in the petrous portion of the temporal bone

Question 7

What are the two labryinths associated with the vestibular organ?

Answer 7

membranous and osseous

Question 8

What is the osseous labyrinth filled with?

Answer 8

perilymph

Question 9

What is the membranous labyrinth filled with?

Answer 9

endolymph

Question 10

Where is endolymph produced?

Answer 10

in the cochlea

Question 11

What are the structural units of the vestibular organ?

Answer 11

three semicircular ducts, utricles, and saccules

Question 12

What are the sensory receptors for the utricle and saccule?

Answer 12

the macula

Question 13

What is the sensory receptor associated with the ampulla?

Answer 13

the crista ampullaris

Question 14

What are the names of the semicircular ducts?

Answer 14

lateral, posterior, and anterior

Question 15

What sensory structures are located in the sensory cells of the crista ampullaris?

Answer 15

one kinocilium and multible stereocilia

Question 16

What do the supporting cells of the crista ampullaris produce?

Answer 16

cupula - gelatinous substance

Question 17

Where is the cupula located?

Answer 17

it is attached to the roof of the ampulla

Question 18

What does the cupula cover?

Answer 18

it encapsulates the stereocilia

Question 19

Where is the macula located?

Answer 19

in the utricle and the saccule

Question 20

What do the supporting cells of the macula produce?

Answer 20

statoconial membrane

Question 21

What is the statoconial membrane made up of?

Answer 21

gelatinous substance and statoconia (Ca carbonate crystals)

Question 22

What is the function of the sensory cells in the vestibular system?

Answer 22

they generate spontaneous firing of vestibular axons

Question 23

What does the firing rate of vestibular axons reflect?

Answer 23

the deflection of stereocilia

Question 24

If the stereocilia move towards the kinocilium what happens to the firing rate?

Answer 24

it increases (depolarization)

Question 25

If the stereocilia move away from the kinocilium what happens to the firing rate?

Answer 25

it decreases (hyperpolarization)

Question 26

What moves the sterocilia in the semicircular duct and crista ampullaris?

Answer 26

the endolymph moves due to a turning motion of the head which pushes the cupula to move the sterocilia

Question 27

In the semicircular duct and crista ampullaris, what does the firing rate reflect?

Answer 27

the direction of angular motion

Question 28

In the utriccle/saccule and ampulla, what does the firing rate reflect?

Answer 28

the direction of linear motion and head tilt

Question 29

What occurs to the statoconial membrane during linear movement?

Answer 29

the statoconial membrane lags behind the linear motion or displaces towards the tilted side by the force of gravity

Question 30

What semicircular duct detects angular motion in the horizontal plane?

Answer 30

the lateral duct

Question 31

What semicircular duct detects angular motion in the vertical plane?

Answer 31

the anterior and posterior ducts

Question 32

If the head turns counter clockwise on the horizontal plane, what is the firing rate like on the left and the right side?

Answer 32

the firing rate is increased on the left side and decreased on the right side

Question 33

If the head turns clockwise on the horizontal plane, what is the firing rate like on the left and the right side?

Answer 33

the firing rate is increased on the right side and decreased on the left side

Question 34

Where do the vestibulospinal tracts run?

Answer 34

in the ventral funiculus

Question 35

Where do the vestibulospinal tracts terminate?

Answer 35

in the motor nucleus of the accessory nerve and the spinal motor neurons

Question 36

How many vestibulospinal tracts are there?

Answer 36

4: there are both medial and lateral tracts on both sides

Question 37

What muscles does the vestibulospinal reflex work with?

Answer 37

the extensor muscles

Question 38

What semicircular canals are associated with the vestibulospinal reflex?

Answer 38

anterior and posterior

Question 39

What is the function of the vestibulospinal reflex?

Answer 39

to maintain posture

Question 40

In the vestibulospinal reflex, if the head rotates to the left, what happens to the firing rate on the left and right side?

Answer 40

the firing rate increases on the left side and slows down on the right

Question 41

In the vestibulospinal reflex, if the head rotates to the right what happens to the firing rate on the left and right side?

Answer 41

the firing rate slows down on the left side and increases on the right

Question 42

What is the purpose of the vestibulo-ocular reflex?

Answer 42

to change eye position in response to change in head position

Question 43

What does rotation of the head trigger in the vestibulo-ocular reflex?

Answer 43

physiological nystagmus

Question 44

What is physiological nystagmus?

Answer 44

a combination of slow and quick eye movements in response to continued head rotation

Question 45

What occurs during the quick phase of nystagmus?

Answer 45

eyes turn quickly towards the direction of the head turn

Question 46

What occurs during the slow phase of nystagmus?

Answer 46

eyes turn slowly away from the direction of the head turn

Question 47

A cat presents with abnormal right nystagmus, what side is the lesion/head tilt on?

Answer 47

the left side

Question 48

What structures are associated with the vestibulo-ocular reflex?

Answer 48

vestibular receptors, vestibular nerve, vestibular nuclei, medial longitudinal fasciculus, motor nuclei of CN III, IV, and VI, the flocculonodular lobe of the cerebellum, and the reticular formation