Vestibular System

Question 1

What are the 3 systems that contribute to postural control?

Answer 1

1. vestibular
2. visual
3. somatosensory

Question 2

What are the fxns of the vestibular system?

Answer 2

1. sense and perceive self-motion
2. postural control
3. stabilization of gaze

Question 3

Stabilization of gaze involves the ________-________ reflex.

Answer 3

vestibulo-ocular reflex (VOR)

Question 4

What are 3 elements to postural control?

Answer 4

1. orient to vertical
2. stabilize head
3. control COM

Question 5

Peripheral sensory apparatus components:

Answer 5

1. 3 semicircular canals

2. otoliths

Question 6

Central processor components:

Answer 6

vestibular nuclei

Question 7

Motor output components:

Answer 7

1. VOR (for gaze stability)

2. vestibulospinal (for posture/balance responses)

Question 8

Name 3 broad components to vestibular system:

Answer 8

1. peripheral apparatus
2. central apparatus
3. motor output

Question 9

Peripheral vestibular apparatus and cochlea are imbedded in what bone?

Answer 9

petrous portion of temporal bone

Question 10

What membrane lined chamber houses the vestibular apparatus and cochlea?

Answer 10

membranous labyrinth

Question 11

The VISCOUS fluid that fills the membranous labyrinth chamber is:

Answer 11

endolymph

Question 12

The fluid that fills the space between membrane and bone is:

Answer 12

perlymph

Question 13

How many planes to the 3 semi-circular canals?

Answer 13

3 planes

anterior/posterior/lateral

Question 14

All 3 semicircular canals open at both ends to the:

Answer 14

utricle

Question 15

The extended portion at the end of each semicircular canal is the:

Answer 15

ampulla

Question 16

The hair cell mechanism within the ampulla is called:

Answer 16

crista or “crist”

Question 17

Crista hair cell receptors are covered by:

Answer 17

gelatinous cupula

Question 18

The cupula is exposed it:

Answer 18

endolymph

Question 19

Crista hair cell receptors have protruding _______.

Answer 19

stereocilia

Question 20

The longest sterocilia are the _______, which are arranged in the same direction within each canal.

Answer 20

kinocilum

Question 21

Semicircular Canals detect:

Answer 21

angular acceleration

Question 22

What causes cilia on hair cells to bend?

Answer 22

due to viscosity, with head movement the endolymph lags behind and pushes cupula

Question 23

What results in increased firing rate?

Answer 23

when stereocilia bend TOWARD kinocilum

depolarization (+) of hair cells occurs

Question 24

What results in decreased firing rate?

Answer 24

when stereocilia bend AWAY FROM kinocilum

hyperpolarization (-) of hair cells occurs

Question 25

Baseline firing rate is equal bilaterally at _____ spikes/sec.

Answer 25

80-100 spikes/sec

Question 26

Receptor potentials summate in hair cells and cause:

Answer 26

neurotransmitter release at base of hair cell | AP generation in CN VIII

Question 27

Describe the push-pull arrangement

Answer 27

equal and opposite response of complimentary canals (reciprocal signals) ex: R rotation means increased firing of R lateral canal and decreased firing of L lateral canal

Question 28

Head movement velocity is proportional to

Answer 28

firing rate of CN VIII

Question 29

What two structures make up the otolothic organs?

Answer 29

saccule and utricle

Question 30

Otoliths detect:

Answer 30

linear acceleration | static head position relative to gravity

Question 31

Otolith orientation:

Answer 31

``` saccule = vertical utricle = horizontal ```

Question 32

Otolithic receptor area is called:

Answer 32

macula

Question 33

What makes otoliths sensitive to gravity?

Answer 33

calcium carbonate crystals called otoconia

Question 34

What are the 4 vestibular nuclei?

Answer 34

1. superior 2. inferior (descending) 3. medial 4. lateral (deiter's)

Question 35

Info is conveyed from hair cells by vestibular portion of CN VIII to the ______:

Answer 35

vestibular nuclei

Question 36

Describe central processing of vesicular nuclei?

Answer 36

* different nuclei have different afferent and efferent connections * vestibular nuclei integrate visual and somatosensory info in addition to vestibular

Question 37

Motor output goes down to SC via _______ and up to eye movement nuclei via ______.

Answer 37

down: vestibulospinal tracts up: MLF (medial longitudinal fasiculus)

Question 38

Symptomatology of vestibular dysfxn

Answer 38

``` dizzy light-headed vertigo disequilibrium oscillopsia ```

Question 39

What is oscillopsia?

Answer 39

unstable, moving visual field

Question 40

What is the term for abnormal sense of movement that occurs more with acute unilateral lesions?

Answer 40

vertigo (vertigenous)

Question 41

Common tumor that influences vestibular system?

Answer 41

acoustic schwannoma

Question 42

What are some influences that aging has on vestibular system?

Answer 42

vascular neuropathy central processing stroke