Transcript Physiology of hearing. Vestibular analyzer

Physiology of hearing.
Vestibular analyzer
1 – cochlear nerve;
2 – ventral cochlear
nucleus;
3 – dorsal cochlear
nucleus;
4 – olivar complexes;
5 – accessory nucleus;
6 – lateral lemniscus;
7 – lower hillocs of
quadrigeminal body;
8 – medial genicular
body;
9 – auditory cortex/
Semicircular canal function
• Ampula is enlargement at
one end of semicircular
canal. It has a small crest
on top of which is a
gelatinous mass known as
cupula. Hair cells have
two kinds of cilia –
kinocilium and stereocilia.
• Kinocilium is large cilium
located at one end of hair
cell. Stereocilia are small.
When stereocilia are bent
towards kinocilium, hair
cell is depolarized, i.e.
stimulated.
• When stereocilia are bend away from
kinocilium, hair cell is hyperpolarized, i.e.
inhibited. It occurs because acceleratory force
acts to flow of fluid in semicircular canals during
circular motion of the head or whole the body.
• Hair cells are located along crista ampularis and
protect their cilia in cupula. Hair cells are
secondary sensor cells, which synapse with
neurons. Axons of these nerve cells compose
vestibular nerve.