Vestibular Function

Question 1

what is the function of the vestibular system?

Answer 1

controls posture and balance

Question 2

where is the vestibular system found in the body?

Answer 2

inner ear

Question 3

what are the name of the semi circular membraneous tubes?

Answer 3

labyrinths

Question 4

what bone is the semi circular canals embedded into?

Answer 4

temporal bone

Question 5

what fills the labyrinth tubes?

Answer 5

endolymph

Question 6

state the importance of the structure of the semi circular canals

Answer 6

the canals are at 90 degrees to each other so tubes can detect movement in 3 dimensions

Question 7

state the three structures which make up the vesicular system

Answer 7

• 3 semi circular canals
• utricle
• saccule

Question 8

what is the swelling at the base of the semi circular canals called?

Answer 8

ampulla

Question 9

what structure connects the three semi circular tubes together ?

Answer 9

the utricle

Question 10

where are sensory hair cells found?

Answer 10

ampulla
utricle
saccule

Question 11

what is the utricle and the saccule collectively known as ?

Answer 11

otolith organs

Question 12

what structure in the vestibular system detects linear acceleration?

Answer 12

utricle
saccule
- otolith organs

Question 13

what structure in the vestibular system detects rotational acceleration?

Answer 13

semi circular canals

Question 14

what are the sensory receptors called which are present in the ampulla?

Answer 14

cristae

Question 15

how many ampulla are there in the inner ear?

Answer 15

3

- one of each semi circular canal

Question 16

what is the gelatinous structure which structure across the ampulla ?

Answer 16

cupula

Question 17

how does the endolymph in the semi circular canals affect the ampulla?

Answer 17

when the endolymph moves in one direction the crista and cupula is pushed in the same way. This affects the cilia of the hair cells which directly synapse with the vestibular nerve.

Question 18

state the two types of cilia of the hair cells

Answer 18

• kinocilium

- sterocilia

Question 19

which of the two hair cell cilia are longer ?

Answer 19

kinocilium

Question 20

state how rotational acceleration is detected when the head is rotated suddenly

Answer 20

1. the ampulla moves with the bone
2. endolymph stays stationary for a moment due to its own inertia
3. the endolymph then produces drag and bends the cupula in the opposite direction
4. as the endolymph catches up with the acceleration the cupula becomes unbent
5. at a sudden stop, the bone stop moving so the ampulla is stationary but the endolymph still has its momentum so continues the path it had.
6. this causes the cupula to be bent in the opposite direction
7. this causes sense of movement and dizziness

Question 21

distortion of cilia towards the kinocilium causes ?

• depolarisation
• hyper polarisation

Answer 21

depolarisation

- increase APs

Question 22

distortion of cilia towards the stereocilia causes ?

• depolarisation
• hyper polarisation

Answer 22

hyper polarisation

- decrease APs

Question 23

what is the function of the different cilia in the hair cells?

Answer 23

allows the brain to determine movement in time and space

Question 24

where does most of the integration of sensory information take place?

Answer 24

cerebellum

Question 25

what are the sensory apparatus in the utricle and saccule called?

Answer 25

maculae

Question 26

is the macula in the utricle in a - horizontal plane? - vertical plane ?

Answer 26

horizontal

Question 27

is the macula in the saccule in a - horizontal plane? - vertical plane ?

Answer 27

vertical

Question 28

where do the cilia sit in the maculae ?

Answer 28

the cilia are in the gelatinous mass called the otolith membrane

Question 29

whats embedded in the otolith membrane of the maculae ?

Answer 29

otoliths crystals

Question 30

what nerve do the cilia on the hair cells synapse to?

Answer 30

vestibular nerve

Question 31

do the otoliths have a lower or greater density to the endolymph?

Answer 31

greater density

Question 32

when the head is tilted back what happens to the otoliths ?

Answer 32

the otoliths slide backwards towards the direction of the kinocilium causing depolarisation and increased APs

Question 33

when the head is tilted forward what happens to the otoliths ?

Answer 33

the otoliths slide forwards towards the stereo cilia and causes hyper polarisation which decreases APs

Question 34

what part of the vestibular system detects if the head is tilting forward?

Answer 34

the utricle

Question 35

what part of the vestibular system detects if the head is lying down on its side?

Answer 35

the saccule

Question 36

what is the function of the tonic labyrinthine reflexes?

Answer 36

keep the axis of the head in constant relationship with the rest of your body

Question 37

when does the dynamic righting reflex occur?

Answer 37

when you trip | - to prevent you falling over

Question 38

what species is very good at using their dynamic righting reflex?

Answer 38

cats

Question 39

is there a strong association of vision with balance ?

Answer 39

yes | - visual system also sends powerful descending projections which control posture.

Question 40

what is the static reflex of the eyes ?

Answer 40

When you tilt your head, the eyes intort/extort to compensate

Question 41

what can be seen with Dynamic Vestibular Nystagmus ?

Answer 41

A series of saccadic eye movements that rotate the eye against the direction of rotation of the head - quick flick back is away direction travelling

Question 42

if the person is spinning towards the left, what way is the nystagmus ?

Answer 42

right nystagmus

Question 43

what equipment can be used to research about nystagmus ?

Answer 43

Barany chair

Question 44

what is caloric stimulation to research nystagmus ?

Answer 44

when either warm or cold water is poured into the persons ear. the temperature difference causes convention currents which affects the endolymph and causes nystagmus towards or away the affected side depending on the temperature of water poured in

Question 45

what way does the nystagmus go if cold water is poured into the ear?

Answer 45

COWS cold opposite

Question 46

what way does the nystagmus go if warm water is poured into the ear?

Answer 46

COWS warm same

Question 47

lesions where abouts in the CNS can cause nystagmus ?

Answer 47

vestibular pathways

Question 48

what is kinetosis ?

Answer 48

motion sickness

Question 49

what are the symptoms of kinetosis ?

Answer 49

``` nausea vomiting decreases BP dizziness sweating pallor ```

Question 50

what is vertigo?

Answer 50

perception of movement in the absence of movement.

Question 51

what is Ménière’s disease?

Answer 51

Vertigo, nausea, nystagmus and tinnitus

Question 52

what drugs can destroy the hair cells in the inner ear?

Answer 52

streptomycin

Question 53

can vestibular impairment be compensated by the visual system?

Answer 53

yes

Question 54

what are the symptoms of labyrinthitis ?

Answer 54

``` nausea vomiting decreases BP dizziness sweating pallor vertigo ```