Week 1

Question 1

three parts of balance system

Answer 1

vestibular
proprioceptive
visual

Question 2

name the 3 SSCs

Answer 2

horizontal (lateral)
anterior (superior)
posterior (inferior)

Question 3

name the 2 otolith organs

Answer 3

saccule

utricle

Question 4

what type of motion do the SSCs detect?

Answer 4

angular acceleration

Question 5

what is the enlarged end of the SSCs called?

Answer 5

the ampulla

Question 6

what is the goblet shaped structure in the ampulla?

Answer 6

the cupula

Question 7

what is the crista?

Answer 7

the saddle shaped structure under the cupula
*contains cell bodies (hair cells)
kinocilia and stereocilia extend from the crista into the cupula

Question 8

depolarization

Answer 8

when deflection of the stereocilia towards the kinocilia (excitation)

Question 9

hyperpolarization

Answer 9

when deflection of the stereocilia away from the kinocilia (inhibition)

Question 10

otoconia

Answer 10

provide mass the create inertia changes in motion

• embedded in gelatinous material which changes its specific gravity and alters drag
• changes in vertical and horizontal linear accelerations cause excitation and inhibition of the haircells

Question 11

utricular excitation

Answer 11

during horizontal linear acceleration (riding in a car for example) or static head tilt

Question 12

saccular excitation

Answer 12

during vertical linear acceleration (riding in an elevator, changes in gravity)

Question 13

vestibular-ocular reflex (VOR)

Answer 13

an eye movement that occurs in reaction to, or to compensate for a head movement, relatively at the same rate as the head movement

• the eyes will move in the opposite direction of the head
• maintains stable images on the fovea during head motion

Question 14

fovea

Answer 14

a very small area of the retina that allows the clearest/sharpest vision

Question 15

vestibulospinal reflex

Answer 15

• is a reaction to the stimulation of the vestibular labyrinth
• when the head is accelerated to the side there is an ipsilateral extension and a contralateral contraction
• –the limbs ipsi to the direction of acceleration are extended, and limbs contralateral to the acceleration are contracted
• –if a person falls to the left side their left arm will extend out and the right arm will contract inward

Question 16

vestibulocolic reflex

Answer 16

• the purpose of this reflex is to maintain the head in the horizontal position
• the head moves in the opposite direction than the direction of the fall

Question 17

head thrust test

Answer 17

• assesses semicircular canal function
• tested by having patient fixate straight ahead and using a high acceleration head thrust which watching their eyes for then to waver or not (want them to not move and stay focused on the point)

Question 18

head shake test

Answer 18

• have pt tilt chin down 20 degrees and shake head rapidly, do not allow them to fixate their eyes
• upon stopping they should not have nystagmus if their vestib system is normal