Vestibular System

Question 1

where is the vesicular apparatus lcoated

Question 2

describe the layers/ structure of the inner ear-

Answer 2

bony otic capsule- bureid in the lateral part of the petrous bone (part of temporal)

mebrabous labryinth - containign endolymph

perilymph outside

suspending inside bony labyrthth

srussounded by temproal bone

Question 3

Label the image

Answer 3

Vestibular nerve- part of the 8th cranial nerve

cell bodies found in the scarpas ganglion

vestibular organs

ortholith organs- utricel, saccule

smei-cirucal canacls- 3

Question 4

name the 3 semiciruclar canals

Answer 4

Lateral (horizontal semiciruclar) canal

Superiro semi ciruclar canal

Posteiro semicirucla cnaal

Question 5

describe the 2 division of the vesciular apparatus

Question 6

what is the function of the Otolith organs

Answer 6

surface covered in macula- bearing hair cells (steriocillia and kinocillium- absent in cochlear hair cells)

overlying gelatinous gap- scattered over are otoliths- fragments of clacium carbionate

Help respond to chnages ina ngle of head, as gravity or linear changes in position/acceleation of body/head- acts on otoliths

(head tiltied back- sterocillia opull to shortest)- hyperpolairsation

head tilt forward (towaerds kinocillium- tallest)- depolarisation

Question 7

describe how orientation of macula and thus hair cells differences in the otolith organs (utricle vs saccule)

Answer 7

utricle- macula orientated horizontally

saccular- macula orientrated vertically

within both these place,ss terocillia orientated at different angles

Question 8

In summary- utricle and sacciule detect—-

Question 9

what do the semi-circular canasl detect?

Question 10

describe organisation within the semi-cirucalr canal and function

Answer 10

hair cells embeeded in gelatinous cupuila in ampulla

when head rotates- endolymph flows over cupula moving it in opposite direction, due to inertia lags behind - depolarisation of hair cells

left and right semi-cirucalr canals will thus give oppsoite responses

at dsteady speed of rotation, firing rate decreases as the endolymph catches up with the canal (inertia) and moves at same velocity

Question 11

describe the vestibular pathways and the role

Answer 11

Ototlith organs synpase in the lateral vestibular nucleus (cerebellum and limb motor neurones),

Semi-circular canals - medial vestibular nucleus (extraoccilar motor neurones)- controlling the neck

Question 12

describe the Vestibulo-occular reflex

Question 13

what is Nystagmus>

Answer 13

slow movement of eyes in opposite direction to rotation followed by flick back- physiological

sawtootjh wave form

Question 14

describe how motion sickness occurs

Answer 14

vesitublar system and vision giving conflciting signals

Question 15

describe vertigo- what factors cause it

Question 16

what is Menieres disease

Answer 16

affects whole inner ear, vestibular and auditory

symtpoms