Vestibular system

Question 1

What connects the vestibule to the inside of the skull?

Answer 1

vestibular aqueduct

Question 2

Endolymph is manufactured by the:

Answer 2

Stria vascularis

Question 3

Where can you find the christae?

Answer 3

In the ampullae of the semicircular ducts

Question 4

There is a connection between CSF and what fluid of the inner ear?

Answer 4

perilymph

Question 5

What is the potential difference between the endolymph and perilymph?

Answer 5

80 mV

Question 6

What is different about the composision of endolymph compared to perilymph and CSF?

Answer 6

high levels of potassium and low levels of sodium

Question 7

What ensures a steady release of neurotransmitter from the hair cell under resting conditions?

Answer 7

Tip links are attached to motor proteins embedded within the adjacent stereocilium of the hair cell. If tip filament is slack for a long time, motor protein will move upwards and tighten the filament, partially opening K channel

Question 8

Where will you find maculae?

Answer 8

In the saccule and utricle

Question 9

Describe the process by which macula detects sensory information.

Answer 9

Macula has hair cells protruding into gel with otoliths. When linear acceleration in the plane of the organ, the crystals lag behind, depolarizing the hair cells. Note that constant motion does not affect maculae. However, gravity is detected.

Question 10

What is the significance of the striola?

Answer 10

Hair cells on one side are polarized in one way while hair cells on the opposite side are polarized in a different direction. This occurs in the macula

Question 11

If the head is tilted backwards, is depolarization of the macula sustained?

Answer 11

Yes, however there is some slight adaptation over time to firing of vestibular nerve axon

Question 12

What is different about christae from maculae?

Answer 12

No otoliths! Projects into a gelatinous mass called the cupula. Stimulated by movement of fluid within the semicircular canals

Question 13

Each semicircular canal has a corresponding parallel semicircular canal in the other ear. Why is this significant?

Answer 13

Individuals can still detect a full range of motion after destruction of one inner ear

Question 14

Where do the hair cells of the maculae and christae synapse?

Answer 14

vestibular ganglion

Question 15

Where do the first order fibers of the vestibular part of CN VIII synapse?

Answer 15

vestibular complex of nuclei in the rostral medulla

Question 16

The vestibular nuclei also receive input from the flocculus and fastigial nucleus of the cerebellum and spinal cord. Why is this significant?

Answer 16

Needed to adjust the vestibular-ocular reflex–stabilization of the eyes after head movement
Spinal cord=postural adjustments

Question 17

Why is washing the ears with cold water a bad idea?

Answer 17

Can cause vertigo by changing convection currents in the semicircular canals.