PRESENTER: Sound waves
entering the ear travel
through the external
auditory canal
before striking the eardrum
and causing it to vibrate.
The eardrum is connected
to the malleus,
one of three small
bones of the middle ear,
also called the hammer.
It transmits sound vibrations
to the incus, which
passes them to the stapes.
The stapes pushes in and
out against the structure
called the oval window.
This action is passed
on to the cochlea,
a fluid-filled,
snail-like structure that
contains the organ of Corti,
the organ for hearing.
It consists of tiny hair
cells that line the cochlea.
These cells translate vibrations
into electrical impulses
that are carried to the
brain by sensory nerves.
In this cut view, you can
see the organ of Corti
with its four rows
of hair cells.
There is an inner
row on the left
and three outer
rows on the right.
Let's watch this
process in action.
First, the stapes rocks
against the oval window.
This transmits waves of sound
through the cochlear fluid,
sending the organ of
Corti into motion.
Fibers near the upper
end of the cochlea
resonate to lower
frequency sound.
Those near the oval window
respond to higher frequencies.