cochlea duct containing the organ of Corti.
Here is a section. On the left-hand side,
low magnification section through the organ
of Corti, and on the right-hand side, a high
magnification. It shows the organ of Corti
projecting into the endolymph of the cochlea
duct. There's the organ of Corti there. It
has a component, or the endolymph is contained
within the scala media, you see labelled there.
That's the endolymph component of the cochlea
duct. There's a spiral ganglion there.
ganglion is the bipolar neurons that send
dendritic branches to the hair cells in the
organ of Corti. And then the other component
of those ganglion cells sends information
through the cochlea nerve back into the central
nervous system. So that spiral ganglion sits
in the bone adjacent to each coil of the cochlea
duct. The bone is the modiolus that I've explained
earlier. There is two compartments of perilymph, the scala
vestibuli and the scala tympani. Both those compartments, as I
mentioned, contain perilymph. The scala vestibuli
starts at the oval window, and the scala tympani
ends at the round window. They contain perilymph.
And actually those two chambers come together
and the perilymph passes between one on the
other at the very apex of the cupula at a
place called the helicotrema. And you can see
on the left-hand diagram the very apex
part of the cochlea.
So again, the organ of Corti is embedded in
endolymph. Above it, you can see a very small
membrane. That's the vestibular membrane.
And the organ of Corti actually sits on a
basilar membrane, separating the endolymph
from the perilymph of the scala tympani.