Vestibular System

Question 1

What is the vestibular system?

Answer 1

Sensory system essential in control of posture and balance

Question 2

Where is the vestibular system found?

Answer 2

Inner ear

Question 3

What composes the vestibular system?

Answer 3

Series of membranous fluid-filled tubes, embedded in the temporal bone

Question 4

What detects change in movement in the vestibular apparatus?

Answer 4

Hair cells

Question 5

What does the vestibular apparatus consist of?

Answer 5

Three semi circular canals
Utricle
Saccule

Question 6

What contains the sensory hair cells?

Answer 6

Ampulla

Question 7

What are the otolith organs?

Answer 7

Utricle and saccule

Question 8

What is the function of the otolith organs?

Answer 8

Detect liner acceleration and encode information about position of the head in space

Question 9

What positions of the head do the otolith organs detect? (specific)

Answer 9

Utricle - front and back tilt

Saccule - vertical movement

Question 10

What do the semi-circular canals detect?

Answer 10

Rotational acceleration

Question 11

What do the cristae consist of?

Answer 11

Flexible gelatinous structures called cupula

Question 12

What is the function of the cupula?

Answer 12

Responds to movement of the endolymph fluid within the canals

Question 13

What are the cristae?

Answer 13

Sensory receptors in the ampulla of semi circular canals

Question 14

What do the cristae synapse with?

Answer 14

Sensory neurons of the vestibular nerve

Question 15

Why, if the skull is rotated, does the endolymph not move at first?

Answer 15

Inertia

Question 16

What does the inertia of the endolymph cause?

Answer 16

Produces drag which bens the cupula and consequently the cilia in the opposite direction to the movement

Question 17

What are the two types of cilla of the hair cells?

Answer 17

Kinocillum and sterocilia

Question 18

What does distortion of the cilia in direction of the kinocilium cause?

Answer 18

Depolarisation and increased discharge of APs in the vestibular nerve

Question 19

What does distortion of the cilia away from the kinocilium lead to?

Answer 19

Hyperpolarisation and decreased discharge of APs in the vestibular nerve

Question 20

What does the change in discharge of APs dependent on direction of movement allow for?

Answer 20

Brain to determine movement in time and space

Question 21

Where does most of the integration of the sensory information from the vestibular system take place?

Answer 21

Cerebellum

Question 22

What are the sensory apparatus of the saccule and utricle collectively known as?

Answer 22

Maculae

Question 23

How are the macula orientated in the saccule and utricle?

Answer 23

Horizontal plane in the utricle

Vertical pain in the saccule

Question 24

What are otoliths?

Answer 24

Calcium carbonate crystals embedded in the otolith membrane

Question 25

What do the vestibular nuclei project to?

Answer 25

Ipsilaterally, bilaterally and contra laterally to descending motor pathways Via thalamus to cerebral cortex - perception of movement and body movement

Question 26

What do the vestibular nuclei receive input from?

Answer 26

Proprioceptors signalling limb and body position - also neck and eye muscles

Question 27

What tracts do the vestibular system reflexes involve?

Answer 27

Vestibulocortical and vestibulospinal tracts

Question 28

What are the tonic labyrinth reflexes?

Answer 28

Keep the axis of the head in a constant relationship with the rest of the body. Uses information from maculae and neck proprioceptors

Question 29

What are the dynamic righting reflexes?

Answer 29

Rapid postural adjustments that are made to stop you falling when you trip

Question 30

What is dynamic vestibular nystagmus?

Answer 30

Series of saccadic eye movements that rotate the eye against the direction of rotation of head and body so that original direction of gaze is preserved Exent of eye movement restricted when eyeball comes to end of its range off movement

Question 31

What do afferents from the semi-circular canals project and connect to?

Answer 31

Afferent fibres travelling to the extraocular muscles and thus have strong input to influencing eye movement

Question 32

What does an acute interference with normal vestibular function as a result of infection result in?

Answer 32

All ANS symptoms and vertigo

Question 33

What is vertigo?

Answer 33

Perception of movement in the absence of movement

Question 34

What are the symptoms of Meniere's disease?

Answer 34

Vertigo Nausea Nystagmus Tinnitus

Question 35

What is Meniere's disease?

Answer 35

Associated with subjective noise, associated with over production of endolymph causing increased pressure

Question 36

What drug can affect the inner ear?

Answer 36

Streptomycin

Question 37

What can lesions of the brain stem cause? (in relation to vestibular system)

Answer 37

Nystagmus