Exam 2 - vestibular system

Question 1

vestibular disease

Answer 1

nystagmus w/ fast phase away from side with lesion (post-rotary is normal)
head tilt toward side of lesion
leaning/circling toward side of lesion
strabismus - both eyes and usually ventral or ventrolateral deviation ipsilateral to lesion when nose elevated

Question 2

paradoxical vestibular disease

Answer 2

associated w/ lesions of flocculonodular lobe or cerebral peduncles = signs are contralateral to lesion
nystagmus w/ fast phase towards lesion
head tilt away from lesion
circling/leaning away from lesion

Question 3

how do you diagnose paradoxical vestibular disease

Answer 3

deficits of conscious perception will be ipsilateral to lesion
deficits of voluntary movement will be ipsilateral to lesion
signs of cerebellar dysfunction (ataxia) will be ipsilateral to lesion

Question 4

peripheral conditions of vestibular system

Answer 4

normal proprioception
normal strength/voluntary motor
horizontal/rotary nystagmus
nystagmus doesn’t change when the head position changed “constant”

includes vestibular apparatus in inner ear and/or vestibular division of vestibular cochlear n.

Question 5

central conditions of vestibular system

Answer 5

paresis
loss of proprioception
horizontal, rotary, vertical nystagmus
nystagmus changes with head position “positional nystagmus”

affects vestibular nuclei in pons and/or medulla

Question 6

vestibular system

Answer 6

stable orientation in relation to gravity and movement
orientation of eyes, neck, trunk limbs in reference to movement or position of head

Question 7

bony labyrinth is full of _____

Answer 7

perilymph

Question 8

membranous labyrinth is full of ____

Answer 8

endolymph

Question 9

vestibular apparatus made up of _____

Answer 9

utriculus
sacculus
semicircular ducts

Question 10

maculae

Answer 10

neuroepithelium of utriculus and sacculus
detects linear/gravitational acceleration

Question 11

utricle macula

Answer 11

horizontal

Question 12

saccular macula

Answer 12

vertical

Question 13

hair cells composed of _____

Answer 13

stereocilia (many)
kinocilium (one)

Question 14

the stimulus of hair cells

Answer 14

bending of cilia towards or away from kinocilium
towards = depolarization
away = hyperpolarization

Question 15

hair cells of vestibular system acceleration/vibrations

hair cells of cochlear system acceleration/vibrations

Answer 15

acceleration

vibrations

Question 16

semicircular ducts

Answer 16

part of membranous labyrinth
filled with endolymph, surrounded by perilymph
detects angular/rotational acceleration

Question 17

crista ampullaris

Answer 17

neuroepithelium of semicircular ducts

Question 18

increased activity of the hair cell
cupula go toward ______
stereocilia bend toward _____

Answer 18

utriculus
kinocilium

Question 19

hyperpolarization
cupula ____
stereocilia _____

Answer 19

buldges away from utriculus
bend away from kinocilium

Question 20

vestibuloocular reflex

Answer 20

focused retinal image when head moves
movement of eyes in opposite direct of head
nystagmus
medial longitudinal fasciculus (MLF)

Question 21

vestibulocolic reflex

Answer 21

descending portion of MLF = medial vestibulospinal tract
neck movement and forelimb extension that counteract tilt of head
increases extension of ipsilateral neck and forelimb to side of acceleration

Question 22

vestibulospinal reflex

Answer 22

lateral vestibulopsinal tract
limb extension that counteracts the displacement of the head that elicits it
extension of ipsilateral forelimb and hindlimb, inhibits ipsilateral flexors and inhibits contralateral extensors

Question 23

Vestibular reflexes are based on a ______________ of the signals coming from left & right vestibular apparatus; it is the _______________ between the two sides which __________

Answer 23

comparison
asymmetry of firing
drives the reflexes