Vestibular

Question 1

Stimuli for vestibular system

Answer 1

angular and linear accelerations of the head

Question 2

2 parts of vestibular apparatus

Answer 2

Semi circular canals and otolith organs

Question 3

Otolith organs

Answer 3

Utricle and saccule - detect linear acceleration

Question 4

Semi-circular canals in size order and planes

Answer 4

Posterior (coronal plane) - crack neck
Anterior (sagittal plane) - nod head
Horizontal (transverse plane) - shaking head

Question 5

The ampulla and function

Answer 5

At duct in semicircular canals, detects changes in pressure of fluid at the cupula which moves stereocilia of hair cells

Question 6

Semicircular canal signal transduction

Answer 6

Stimulation and inhibition of resting activity *depolarisation and hyperpolarisation

Question 7

Movement of hair cells towards longest cilia

Answer 7

Stimulation and depolarisation due to mechanically gated channels opening and influx of K+

Question 8

Movement of hair cells towards shortest cilia

Answer 8

Inhibition and hyper-polarisation as the K+ channels close even more

Question 9

Utricle orientation

Answer 9

horizontal when standing, hair cells sit vertically - detect horizontal speed

Question 10

Saccule orientation

Answer 10

vertical when standing, hair cells sit horizontally - detect falling

Question 11

Otoconia

Answer 11

Calcium carbonate crystals that weigh down the liquid preventing the liquid from distending the membrane of the otolith organs

Question 12

Macula

Answer 12

Hold hair cells in the otolith organs

Question 13

Axons project to:

Answer 13

Vestibular nuclei in brainstem

Question 14

Vertigo

Answer 14

Caused by disease affecting the vestibule of its afferent fibres (illusion of movement, dizziness)

Question 15

Motion Sickness

Answer 15

Causes by mismatch of eyes and ears

Question 16

“Bedspins”

Answer 16

Ethanol infiltrates cupula, lowers density and causes it to “float”, bending hair cells and creating perception of movement

Question 17

Acoustic neuroma

Answer 17

Tumour along vestibulocochlear nerve

Question 18

Meningitis

Answer 18

Inner ear invasion by bacteria

Question 19

Ototoxic drugs

Answer 19

Can result in temporary and permanent hearing loss

- Antibiotic are the worst culprits

Question 20

Vestibular rehabilitation

Answer 20

Gaze stabilisation (remaining focused on a moving object) and habituation (controlled stimuli that give us dizziness or nausea)