OT 6000 Test 5- Ch 22

Question 1

Vestibular system function

Answer 1

• Works to keep us visually and physically steady to the world
• contributes to maintenance of balance and equilibrium

Question 2

Semicircular canals

Answer 2

Between all 3 (posterior, anterior and horizontal) they can detect any movement

• 3 per side of head
• contain hair cells in fluid that constantly send signals (baseline activity) on head position based on hair cell movement

Question 3

Depolarization of semicircular canals

Answer 3

Semicircular canals detect angular movement of the head by INCREASING AP’s on the side your head is turning towards and DECREASING AP’s on the side you’re turning away from

Question 4

Semicircular canals paired activity

Answer 4

It takes pairing to tell brain which way your head is moving:

• R anterior and L posterior detect movement in one plane
• L anterior and R posterior detect movement in one plane
• R and L horizontal detect movement in one plane

Question 5

Otolithic organs

Answer 5

• utricle: detects horizontal movement and pull of gravity
• Saccule: detects linear movement and pull of gravity
• ->Ampula are located at end of canals and contain hair follicles and oticonia crystals

Question 6

Vestibular Nuclei

Answer 6

Is the central processor of equilibrium system: gathers all sensation information and determines what needs to be done to stay upright

• Send signals to Mm that control head to cause it to stay upright against gravity
• excites the medial longitudinal fasciculus (MLF) to keep vision steady by keeping eyes together
• ->gathers information in forms of proprioception, vision, equilibrium, auditory and tactile

Question 7

Reciprocal inhibition of visual cortex and vestibule

Answer 7

• Increased visual cortex activity inhibits the vestibular cortex
• Increased vestibular cortex activity inhibits the visual cortex

Question 8

Pusher syndrome

Answer 8

Pathways from inner ear to cortex are damaged and pt feels like they are falling over, they then try to push themselves upright and end up pushing themselves over

Question 9

Oscillopsia

Answer 9

No gaze stabilization. A condition caused by:

• complete lack of gaze stabilization
• complete lack of VOR

Question 10

Dysequilibrium

Answer 10

Impaired gaze stabilization- will perceive world as blurry

-VOR not working, either in one or both eyes

Question 11

Unilateral Hyperfunction

Answer 11

Example: BPPV

• One side signals excess movement on one side of head when at rest (in direction of pathology)
• leads to nausea, reduced gaze stabilization, poor posture control and vertigo

Question 12

Unilateral Hypofunction

Answer 12

Example: neuritis (one side of nerve compressed to weaken signal)

• input in side that is affected decreased or goes away while at rest and moving
• leads to gaze instability (world blurry when turning head) and postural instability
• ->will not report nausea or vertigo (no acute mismatch)

Question 13

CN VIII

Answer 13

Vestibularchoclear: balance and hearing

-Ends between pons and medulla