Vestibular Function

Question 1

What is the vestibular system?

Answer 1

Inner ear structure containing series of fluid filled membraneous tubes (labyrinths) which are embedded in the temporal bone

Question 2

How many circular canal are there?

Answer 2

Three arranged at right angles to cover three dimensional space

Question 3

Describe the structure of the semi-circular canal

Answer 3

Swelling at base (ampullae) containing sensory hairs

Inside are the receptors (cristae) which consist of gelatinous structure (cupola) which responds to the movement of endolymph

Question 4

What structures detect rotational acceleration?

Answer 4

Hair cells

Question 5

Sudden cessation of movement causes a series of dizziness/nausea, why?

Answer 5

Newfound intertia of endolymph

Question 6

What two types of hair cells are there?

Answer 6

Kinocilium (single large hair)

Stereocilia (multiple small hairs)

Question 7

Distortion in the direction of the kilocilium causes what nerve response

Answer 7

Increased frequency of vestibulocochlear nerve

Question 8

How does the arrangement of the cupulae act in conjunction with the cerebellum to compose a three dimensional perception of the body

Answer 8

Cupulae all arranged differently

Question 9

What comprises the otolith organs?

Answer 9

Utricle and saccule

Question 10

What cavernous structure sits at the base of the ampullae of the semi-circular canals?

Answer 10

Maculae

Question 11

What do maculae contain?

Answer 11

A set of cilia which protrudes into a gelatinous mass of otolith membrane

Question 12

What can be said about the structure of the otolith membrane?

Answer 12

Contains otoliths (CaCO3) crystals

Question 13

What is the function of otoliths?

Answer 13

Affected by gravity more than endolymph then detected which gives information about the position of the head

Question 14

Other than position of the head, what other sensation do otoliths detect?

Answer 14

Linear sensation

Question 15

Name the vestibular reflexes?

Answer 15

1. Static reflex
2. Post-retatory nystagmic reflex
3. Caloric stimulation reflex
4. Dynamic reflex

Question 16

What is the static vestibular reflex?

Answer 16

Intorsion and extortion when the head tilts

Question 17

Describe the dynamic reflex nystagmic reflex

Answer 17

Saccadic eye movements that rotates the eye (nystagmus) in the opposite direction of movement

Question 18

What device is used to detect a dynamic vestibular reflex?

Answer 18

Barany chair

Question 19

What is the pneumonic indicating the outcomes of the caloric stimulation reflex?

Answer 19

COWS

Question 20

What is the danger of using too hot or cold water in the caloric stimulation test?

Answer 20

Reflex too strong, results in nausea/dizziness

Question 21

What is vertigo?

Answer 21

Perceptual hallucination of movement in the absence of movement

Question 22

What is Menieres Disease?

Answer 22

Overproduction of endolymph causing vertigo, tinnitus, nausea and nystagmus

Question 23

What is the aetiology of Meniere’s Disease?

Answer 23

Unknown

Question 24

What other factors can cause vestibular pathology?

Answer 24

Brainstem lesion

Chronic vestibular impairment

Drugs e.g. streptomycin

Question 25

How is chronic vestibular impairment well compensated for?

Answer 25

Learning circuits can be developed to use vision and a queue for proprioception