-
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.