Vestibular System

Question 1

Vestibular system

Answer 1

Provides sense of balance and body position

Question 2

Functions of vestibular system

Answer 2

• control and coordinate movements
• help maintain tone and posture
• stabilize images on the retina/fovea when the head moves
• equilibrium and balance

Question 3

Labyrinth parts

Answer 3

• semicircular canals (3)
• utricle
• saccule

Question 4

Utricle and saccule function

Answer 4

Respond to linear accelerations of the head and static position

Question 5

Semicircular canals function

Answer 5

Respond to rotational accelerations

Question 6

Hair cells

Answer 6

Special sensory receptors of the inner ear; mechanoreceptors

Question 7

Hair cells in semicircular canal are in

Answer 7

Cristae

Question 8

Hair cells in utricle and saccule are in

Answer 8

Maculae

Question 9

If stererocilia (microvilli) bend towards kinocilium (cilia), there is:

Answer 9

Depolarization and NT release

Question 10

If stereocilia move away from kinocilium, there is:

Answer 10

Inhibition or hyperpolarization of the cell

Question 11

3 fluid (endolymph) filled canals

Answer 11

• anterior (inferior)
• posterior (superior)
• horizontal (lateral)

Question 12

Ampullae

Answer 12

Opening of the canal into the utricle

Question 13

Cupula is displaced by

Answer 13

Rotational acceleration

Question 14

Endolymph and cupula move in:

Answer 14

Opposite direction of head rotation; head moves left: endolymph moves to right, left vestibular nerve stimulated, right inhibited

Question 15

Semicircular canal pairs

Answer 15

• R inferior (posterior) and L superior (anterior)
• R and L horizontal
• R superior and L inferior

Question 16

Information from the right and left is sent to the____ and integrated in ____

Answer 16

Vestibular nuclei; CNS

Question 17

Maculae

Answer 17

Sensory organ of the saccule and utricle

Question 18

Utricle movement detection

Answer 18

Horizontal movement

Question 19

Saccule movement detection

Answer 19

Vertical movement

Question 20

Vestibular nuclei

Answer 20

Cranial nuclei for the vestibular nerve located in the brainstem; 4 on each side

Question 21

Vestibular nuclei projections

Answer 21

• cerebellum
• spinal cord
• motor nuclei of extraocular eye muscles in brainstem MLF (medial longitudinal fasciclus)
• thalamus

Question 22

Cerebellum

Answer 22

Controls posture and coordinates movement

Question 23

Vestibulospinal pathways

Answer 23

• Descending medial longitudinal fasciculus (medial vestibulospinal tract)
• vestibulospinal tract (lateral vestibulospinal tract)

Question 24

Descending medial longitudinal fasciculus (medial vestibulospinal tract)

Answer 24

Descends to the level of the neck to control head and neck movements

Question 25

Vestibulospinal tract (lateral vestibulospinal tract)

Answer 25

Descends entire level of the cord to control ipsilateral posture

Question 26

Cranial nerves involved in extraocular eye muscle movements

Answer 26

Occulomotor, trochlear, abducens

Question 27

Motor nuclei of extraocular eye muscles pathway

Answer 27

Ascending medial longitudinal fasciculus

Question 28

Vestibulo-ocular reflex (VOR)

Answer 28

Coordinates eye muscles so that the image stays focused on retina/fovea even when head is rotating

Question 29

Medial longitudinal fasciculus (MLF)

Answer 29

- correlates movements of eyes, face, tongue, neck in relation to vestibular, hearing or visual stimuli - ascends to cranial nerves - descends to medial vestibulospinal tract - projects bilaterally

Question 30

Vestibular nuclei projections to spinal cord (cervical)

Answer 30

- medial vestibulospinal tract or descending part of the medial longitudinal fasciculus - coordinate head and neck with eyes

Question 31

Vestibular nuclei projections to spinal cord (entire)

Answer 31

- lateral vestibulospinal tract or vestibulospinal tract - involuntary control of postural muscles esp extensors

Question 32

Occulomotor nerve (III) motor nuclei projection

Answer 32

Somatic motor to medial, inferior, superior rectus and inferior oblique, levator palpebrea superioris

Question 33

Trochlear nerve (IV) motor nuclei projection

Answer 33

Somatic motor to superior oblique

Question 34

Abducens nerve (VI) motor nuclei projection

Answer 34

Somatic motor to lateral rectus

Question 35

Motor nuclei of extraocular muscles

Answer 35

MLF ascending tract carries fibers from the vestibular nuclei to the lower motor neurons of cranial nerves III, IV, VI