Vestibular System

Question 1

Why is balance important?

Answer 1

Fundamental for daily activities: walking, driving, sense of stability and well being
Losing balance is debilitating

Question 2

____ are leading cause of fatal and non fatal injuries in older adults

Answer 2

Falls

Question 3

Dizziness vs vertigo:
What is dizziness?
What is vertigo?

Answer 3

Dizziness: unsteadiness, feeling faint, feeling weak
Vertigo: false sensation that the individual or the environment is moving

Question 4

What are the two main components of the balance system?

Answer 4

Sensory component: what the body tells us about our surroundings
Motor component: what we do to keep our body balanced

Question 5

In order to be balanced, what two systems need to work properly?

Answer 5

Sensory and motor

Question 6

What does the vestibular system do?

Answer 6

• Provides info to the CNS for control of skeletal muscle for postural adjustments
• Stabilizes visual environment during movement
• Provides CNS with spatial info about linear and angular acceleration

Question 7

What are the primary structures of the vestibular system?

Answer 7

Semicircular canals (3 per side)
Utricle
Saccule

Question 8

Of the primary structures, which are responsible for angular acceleration and which are responsible for linear acceleration?

Answer 8

• Semicircular canals: angular acceleration
• Utricle: linear acceleration (horizontal)
• Saccule: linear acceleration (vertical)

Question 9

Utricle and saccule anatomy:

What is the macula?

Answer 9

Vestibule with sensory cells

Question 10

Utricle and saccule anatomy:

What is otolithic membrane?

Answer 10

Gelatinous membrane covered in calcium carbonate crystals (otoconia)

Question 11

Utricle and saccule anatomy:

Where are the hair cells?

Answer 11

Embedded in the otolithic membrane

Question 12

Utricle and Saccule anatomy:

What are otoconia?

Answer 12

Calcium carbonate crystals with higher specific gravity than surrounding endolymph

Question 13

Utricle and saccule:

Stereocilia face which direction

Answer 13

Opposite directions

Question 14

Hair cells in the utricle and saccule are oriented so each utricle/saccule serve as …

Answer 14

Its own functional pair (have a pair within themselves)

Question 15

The utricle/saccule also get information from …

So they have ___ and ___ pairing

Answer 15

• contralateral side

- have an equal (within the structure) and opposite (on the other side) pairing

Question 16

Semicircular canals are responsible for ….

Answer 16

Angular motions, think of a plane

Question 17

Semicircular canals are paired to the other ear in the following manner

Answer 17

Right anterior to left posterior (RALP)
Left anterior to right posterior (LARP)
Right horizontal to left horizontal

Question 18

What is the function of the semicircular canals?

Answer 18

• Have excitatory/inhibitory relationship with partner canal
• Brain integrates information from all three pairs to form a representation of head movement relative to space

Question 19

Semicircular canal anatomy:

What is the ampulla?

Answer 19

Houses the sensory epithelium of each SSC

Question 20

Semicircular canal anatomy overview

Answer 20

Hair cells sit in the crista ampullaris and are imbedded in the cupula

Question 21

Semicircular canals:

In what direction do the stereocilia face?

Answer 21

Stereocilia face the same direction

Question 22

The eyes form the ___ system that is connected to _____ muscles via _____

Answer 22

Peripheral vestibular system, extraocular, brainstem

Question 23

There are _ extraocular muscles, each controlling eye motion in a ____ direction
Each muscle pairs with specific ____ ______

Answer 23

6, different

Semicircular canals

Question 24

Stimulation of the semicircular canals results in the movement of the paired extraocular eye muscles.
This is also called …

Answer 24

Also called VOR, vestibulo-ocular reflex

Question 25

Why do we care about the vesibulo ocular reflex?

Answer 25

Helps keep our eyes on target, disruption indicates nystagmus

Question 26

What is nystagmus?

Answer 26

Eye twitching that is a sign of vertigo

Question 27

What are the different vestibular tests?

Answer 27

o Videonystagmography (VNG) testing
o Whole-Body Rotational Chair Test
o Video Head-Impulse Test (vHIT)
o Vestibular evoked myogenic potentials (VEMPs)
o Computerized dynamic posturography (CDP)
o Sensory organization test (SOT)