Vestibular System

Question 1

What does the vestibular system control?

Answer 1

Posture and balance

Question 2

Where is the vestibular system found?

Answer 2

Inner ear (labyrinths embedded in temporal bone)

Question 3

What does the vestibular apparatus consist of?

Answer 3

3 semicircular canals
Utricle
Saccule

Question 4

What are the utricle and saccule collectively known as?

Answer 4

Otolith organs

Question 5

What do the otolith organs detect?

Answer 5

Linear acceleration

Encode info about position of head

Question 6

What is the function of the utricle?

Answer 6

Back/front head tilting

Question 7

What is the function of the saccule?

Answer 7

Vertical movement

Question 8

What do the semicircular canals detect?

Answer 8

Rotational acceleration

Question 9

Where are the sensory cells located in the semicircular canals?

Answer 9

Ampulla (base of ssc)

Question 10

What are cristae?

Answer 10

Sensory receptors consisting of capula which stretch across ampulla and respond to movement of endolymph fluid

Question 11

What are found in the capula?

Answer 11

Cilia of hair cells which directly synapse with sensory neurons of vestibular nerve

Question 12

What do the hair cells in the scapula detect?

Answer 12

Rotational acceleration

Question 13

How do the hair cells respond to rotational acceleration?

Answer 13

Endolymph inertia produces drag, bends the capula and cilia in opposite direction to movement
Sudden stop- endolymph still moves, sense of movement and dizziness

Question 14

What are the 2 types of cilia?

Answer 14

Kinocilium

Stereocilia

Question 15

What is the effect of cilia distortion in direction of kinocilium?

Answer 15

Depolarisation and increased APs in vestibular nerve

Question 16

What is the effect of cilia distortion in direction away from kinocilium?

Answer 16

Hyperpolarisation and decreased discharge of APs in vestibular nerve

Question 17

What is the sensory apparatus of the utricle and saccule known as?

Answer 17

Maculae

Question 18

How are the maculae different within the otolith organs?

Answer 18

Utricle - orientated on horizontal plane

Saccule - orientated on vertical plane

Question 19

What is the tonic labyrinthine reflex?

Answer 19

Keeps head axis in constant relationship with rest of body

Question 20

What is the dynamic righting reflex?

Answer 20

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

Question 21

What is vertigo?

Answer 21

Perception of movement in the absence of movement

Question 22

What symptoms are associated with Meniere’s disease?

Answer 22

Vertigo
Nausea
Nystagmus
Tinnitus

Question 23

What are the CaCO3 crystals found in the otolith membrane called?

Answer 23

Otoliths

Question 24

What detects head tilting?

Answer 24

Macula in utricle

Question 25

What does head tilting cause?

Answer 25

Otoliths and otolith membrane move, distorts jelly and moves cilia

Question 26

What is static reflex?

Answer 26

Eyes intort/extort to compensate for head tilting so image stays the right way up

Question 27

What is dynamic vestibular nystagmus?

Answer 27

Eye movements that rotate the eye against direction of rotation of head and body so that direction of gaze is preserved

Question 28

How is vestibular function tested?

Answer 28

Post rotatory nystagmus

Caloric stimulation