Monday, December 27, 2010

Organ of Corti

Organ of corti is the sense organ of hearing and is situated
on the basilar membrane. Important components of
the organ of corti are:
1. Tunnel of Corti, which is formed by the inner and
outer rods. It contains a fluid called cortilymph. The exact
function of the rods and cortilymph is not known.
2. Hair cells. They are important receptor cells of
hearing and transduce sound energy into electrical energy.
Inner hair cells form a single row while outer hair cells are
arranged in three or four rows. Inner hair cells are richly
supplied by afferent cochlear fibres and are probably more
important in the tranmission of auditory impulses. Outer
hair cells mainly receive efferent innervation from the
olivary complex and are concerned with modulating the
function of inner hair cells.
3. Supporting cell. Deiters' cells are situated between
the outer hair cells and provide support to the latter.
Cells of Hensen lie outside the De iters' cells.
4. Tectorial membrane. It consists of gelatinous
matrix with delicate fibres. It overlies the organ of Corti.
The shearing force between the hair cells and tectorial
membrane produces the stimulus to hair cells.
Nerve Supply of Hair Cells: 95% of afferent fibres of spiral ganglion
supply the inner hair cells while only 5% supply the outer
hair cells. Efferent fibres to the hair cells come from the
olivocochlear bundle. Their cell bodies are situated in
superior olivary complex. Each cochlea sends innervation
to both sides of the brain.

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