Vestibular System

Question 1

What are the receptors in the vestibular system and where are they located?

Answer 1

The labyrinthine apparatus in the inner ear - the receptors are vestibular hair cells

Question 2

What is the role of the semi-circular canals?

Answer 2

Detects angular movement of the head (rotation)

Question 3

How do semi-circular canals detect rotation?

Answer 3

1) Head rotates
2) Force is created by inertia of the endolymph (fluid in canals)
3) This causes hair cell displacement in capula
4) This causes an action potential in the ampullary nerve

Question 4

What is the role of the utricle/saccule?

Answer 4

Detects tilt of the head and acceleration/deceleration

Question 5

How does the utricle/saccule detect head tilt?

Answer 5

1) Head tilts/ accelerates
2) Hair cells bend due to movement of otolithic membrane
3) Action potential is generated

Question 6

What is the role of the vestibulo-ocular-reflex?

Answer 6

Enables the eyes to move in the opposite direction and at an equal velocity to the head

Question 7

What is the role of vestibulo-spinal reflexes?

Answer 7

To maintain/regain postural control through activation of vestibulospinal pathways

Question 8

Describe the whole vestibulospinal pathway

Answer 8

1) The hair cell sends a message to the vestibular nucleus
2) The vestibular nucleus sends information of our head position to the vestibulocerebellum and in return received information about somatosensation which it receives from the spinocerebellar pathways
3) This allows the cerebellum to modulate the output of vestibular nuclei
4) This output either travels down the lateral or medial tract (medial = reflex control in neck muscles)(lateral = limb muscles)
5) There is also a pathway directly from the hair cells to the vestibulocerebellum alerting it to upcoming information