Week 1: Anatomy and Physiology of the Vestibular System

Question 1

What are the functions of the vestibular system?

Answer 1

1. Position and perceiving self-motion
2. Sensory orientation
3. Postural responses
4. Stabilizing the head

Question 2

Head movements are detected by the _______ and transmitted via the _______ to the _______, which then controls ________ to ________.

Answer 2

Cupula
Vestibular nerve
Brain
Eye movements
Stabilize gaize

Question 3

What should the ratio of eye to head movement (GAIN) be? What does abnormal gain cause?

Answer 3

1:1

Blurry vision or vertigo

Question 4

What does the Vestibuo-Ocular Reflex (VOR) do?

Answer 4

Stabilizes eye in space, necessary to see while head is in motion

Question 5

What are the 2 components of VOR?

Answer 5

Linear and angular

Question 6

What does the Vestibulo-Spinal Reflex (VSR) do?

Answer 6

Stabilizes body, helps maintain desired orientation to environment

Question 7

What does the Cervico-Ocular Reflex (COR) do?

Answer 7

weak, does not play a direct role in gaze stability, may help VOR compensate via proprioceptors and somatosensory receptors

Question 8

Where do the propriocecptors and somatosensory receptors for the COR arise?

Answer 8

C1-C2 dorsal nerve roots

Question 9

What does the Cervicocollic Reflex (CCR) do?

Answer 9

provides head stability, contraction of stretched muscles to align head

Question 10

What does the Cervicospinal Reflex (CSR) do?

Answer 10

acts in conjunction with the VSR, provides postural stability through the limb activation

Question 11

What are the three axes of rotation?

Answer 11

roll, pitch, yaw

Question 12

What are the three axes of translation?

Answer 12

AP, Lateral, Vertical

Question 13

______ are angular rate sensors.

Answer 13

Semicircular Canals

Question 14

______ are linear accelerometers

Answer 14

Otoliths (Utricle and Saccule)

Question 15

What are the functions of the peripheral vestibular system?

Answer 15

Stabilization of visual images on the fovea of the retina during head movement to allow clear vision, maintain postural stability- especially during head movement, provide information used for spatial orientation

Question 16

What are the components of the peripheral vestibular system?

Answer 16

Semicircular canals, utricle, saccule, CN VII (vestibulocochlear nerve)

Question 17

What are the orientations of the semicircular canals?

Answer 17

Anterior, Posterior, Horizontal

Question 18

What is the bony labyrinth composed of?

Answer 18

3 semicircular canals, the cochlea, and the vestibule

Question 19

What is the bony labyrinth filled with?

Answer 19

perilymphatic fluid

Question 20

What is the membranous labyrinth?

Answer 20

suspended in the bony section and contains portions of the canals and the utricle and saccule.

Question 21

What is the membranous labyrinth filled with?

Answer 21

endolymphatic fluid

Question 22

What are the motion sensors?

Answer 22

Ampulla and Otolith Organ

Question 23

What are cupula?

Answer 23

hair cells

Question 24

What do cupula do?

Answer 24

convert displacement into neuro firing thru bending of hair cells to detect linear/angular motion

Question 25

What contains the otoconia?

Answer 25

utricle and saccule

Question 26

What are otoconia made out of?

Answer 26

calcium carbonate

Question 27

What do shifts in the otoconia cause?

Answer 27

set off neuro firing detecting gravity and acceleration

Question 28

Hair cells protrude their processes into a gelatinous matrix called ______.

Answer 28

macula

Question 29

The firing rate of the otoconia is ______ for ipsilateral linear head movement or tilt.

Answer 29

Increased

Question 30

The firing rate of the otoconia is ______ for contralateral linear head movement or tilt.

Answer 30

Decreased

Question 31

________ measure linear acceleration and lateral tilt

Answer 31

Otoliths

Question 32

What are the 2 targets for vestibular input?

Answer 32

vestibular nuclear complex and the cerebellum

Question 33

_______ is the main adaptive processor.

Answer 33

cerebellum

Question 34

_______ is the "back up" system for the adaptation of the gain of the VOR

Answer 34

cerebellum

Question 35

What is the main supplier of both the peripheral and central vestibular systems?

Answer 35

vertebrobasilar artery

Question 36

Occlusion of which arteries causes clinical syndromes with vestibular components?

Answer 36

basilar, labyrinthine, AICA, PICA

Question 37

Why are cerebella strokes the most commonly missed?

Answer 37

symptoms may mimic vertigo

Question 38

Only ____ sec of ischemia can cause permanent damage

Answer 38

15

Question 39

maintains gaze direction of the eyes and visual acuity during activities involving active head and body movements

Answer 39

gaze stabilization system

Question 40

keeps body in balance while an individual stands and actively moves in daily life

Answer 40

postural stabilization system