Vestibular Function

Question 1

where is the vestibular system

Answer 1

in the inner ear

Question 2

the vestibular system has how many semi-circular canals

Answer 2

3

Question 3

what do the semi-circular canals attaach to

Answer 3

the utricle

Question 4

describe the relation of the semi-circular canals to each other

Answer 4

they are all at right angles with one another so they can detect motion in 3 directions

Question 5

the swelling at the base of the semi-circular canal is called the …

Answer 5

ampulla

Question 6

which parts of the vestibular system contain sensory hair cells

Answer 6

ampulla, utricle and saccule

Question 7

what are the otolith organs

Answer 7

utricle and saccule

Question 8

what is detected by the semi-circular canals

Answer 8

rotational acceleration

Question 9

what is detected by the utricle and saccule

Answer 9

linear acceleration

utricle: back to front
saccule: vertical

Question 10

fluid of semi-circular canals

Answer 10

endolymph

Question 11

structure of cristae

Answer 11

a cupula in endolymph which has cilia embedded in it

Question 12

how does the crista detect movement

Answer 12

rotation of the head creates inertia which moves the endolymph bending the cupula and the cilia within it in the opposite direction of movement.
sterocilia move in the direction of the kinocilium causing depolarisation and APs sent to the vestibular nerve

Question 13

two types of cilia in hair cells

Answer 13

stereocilia and kinocilium

Question 14

what happens when stereocilia distort away from the kinocilium

Answer 14

hyperpolarisation and decreased in APs to vestibular nerve. tell brain they’re travelling in other direction

Question 15

origin of vestibulocochlear nerve

Answer 15

pons

Question 16

what happens when travelling in a direction at a constant velocity

Answer 16

there is no shearing force on the cilia so no APs sent

Question 17

what happens when you stop rotation

Answer 17

there is shearing of the cupula in the opposite direction

Question 18

sensory apparatus of utricle and saccule

Answer 18

maculae

Question 19

which direction are the maculae of the saccule orientated

Answer 19

on the vertical plane

Question 20

structure of maculae

Answer 20

cilia (one kinocilium and many stereocilium) protuding into a gelatinous mass of the otolith membrane. Otoliths (crystals of CaCO3) are embedded in the membrane

Question 21

crystals of what substance are embedded in the otolith membrane

Answer 21

CaCO3

Question 22

why are otoliths more affected by gravity than endolymph

Answer 22

because they are denser, heavier

Question 23

process of otolith organs detecting movement

Answer 23

head tilts –> otoliths follow direction –> distort jelly –> move cilia –> discharge of APs

Question 24

tilting the head back increases/decreases the number of APs sent

Answer 24

increases - moves cilia towards the kinocilium

Question 25

tilting the head forwards increases/decreases the number of APs sent

Answer 25

decreases

Question 26

which organ detects head movement tilting back and forth

Answer 26

utricle

Question 27

where is the vestibular nuclei

Answer 27

in the medulla

Question 28

how does info from the vestibular nerve reach the cortex

Answer 28

vestibular nerve --> vestibular nuclei --> thalamus --> cortex

Question 29

true/false the vestibular nuclei recieves information from up and down an also sends information up and down

Answer 29

true

Question 30

what reflex keep the head in the axis with the body

Answer 30

tonic labrinthine reflex (maculae and neck proprioceptors)

Question 31

what reflex makes rapid postural adjustments when falling/tripping

Answer 31

dynamic righting reflexes

Question 32

why is balancing harder when you close your eyes

Answer 32

because the visual system send descending projections which control posture

Question 33

true/false people with damaged vestibular apparatus can still maintain good balance

Answer 33

true - if the movement is slow and the eyes are open. NOT is eyes are CLOSED

Question 34

what is the static reflex

Answer 34

when you tilt your head and your eyes intort/extort to compensate so the image stays right way up

Question 35

what is nystagmus

Answer 35

involuntary eye movement

Question 36

right nystagmus happens when you rotate _____

Answer 36

right (direction of flick back)

Question 37

when your head rotates right which way should your eyes rotate in the orbit

Answer 37

left

Question 38

what happens in dynamic vestibular nystagmus

Answer 38

the head rotates in a direction and the eyes compensate to stay orientated on the same spot until they reach their limit and flick back

Question 39

what happens in caloric stimulation

Answer 39

one ear warm; one ear cold. endolymph is affection by convection nystagmus occurs in direction of warm ear

Question 40

complications of caloric stimulation nystagmus

Answer 40

nausea and vomiting

Question 41

motion sickness happens when which two systems are in conflict

Answer 41

visual and vestibular

Question 42

what is overproduced in meniere's disease

Answer 42

endolymph

Question 43

presentation of meniere's

Answer 43

vertigo, nausea, nystagmus, tinnitus

Question 44

what is vertigo

Answer 44

feeling of movement when you're still

Question 45

true/false brainstem lesions can cause nystagmus

Answer 45

true