Physiology of Balance

Question 1

What part of the vestibules is responsible for side to side movement?

Answer 1

The macula of the Utricle

Question 2

What part of the vestibules is responsible for up and down movement?

Answer 2

the macula of the saccule

Question 3

What part of the vestibules is responsible for rotational movement?

Answer 3

The semicircular canals.

The crista (surrounded by cupula)

Question 4

What are the layers of the macula that allow for the registration of movement?

Answer 4

Neuroepithelium

Gel layer

Otoconia

Question 5

What are the layers of the Cupula that allow for the registration of movement?

Answer 5

Neuroepithelium and endolymph

Question 6

What is the role of the Kinocilum?

Answer 6

It is the longest hair strand which fires action potentials at a constant rate.

If the others move toward it it increases firing. If they move away it decreases firing

Question 7

What does the term ‘functional pairs’ relate to?

Answer 7

The vestibular ducts in each ear work together and the brain interprets what is going on.

The lateral ducts work together and the Superior works with the posterior and vice versa

Question 8

What role do the extraocular muscles have?

Answer 8

They keep the eye in a fixed position when moving the head and they receive input directly from the semicircular canals

eg lateral ducts connect to the rectus

Question 9

What is a nystagmus and how is classified?

Answer 9

This is when the eye drifts to one side (the affected side) and snaps back to the unaffected side.

It is classified by it’s snapping back phase so a right sided nystagmus means a problem with the left side

Question 10

What are some possible causes of nystagmus?

Answer 10

Menieres

Labyrinthitis

MS

Cerebellum tumour