This cut passes posterior to
the genu
of the corpus
callosum. The cortex is
more prominant and you can see gray areas in the core of the
section.
You can clearly see corpus
callosum crossing the midline in this section. Hanging
down from
the corpus callosum is the septum
pellucidum, a membrane that separates the lateral ventricles.
You are looking rostrally
here and you can still see the rostral
end of
each ventricle. These ventricles now take on a winged shape with
the septum
pellucidum forming the majority of the medial wall of each
ventricle. Each
lateral
wall is formed by the bulbous head of the caudate nucleus. It
is this rounded head that causes the winged appearance of the
ventricles at this level. You might try looking at the medial
face of your uncut brain half and see if you can peek into the anterior
lateral ventricle and see the
shiny head of the caudate peeking
back.
Particularly on the left side of
this section you can see some white and gray spotting
(stipeling). This stipeling is characteristic of the pattern
caused by the white internal capsule
as it courses between the solid dark gray of the caudate and the
lighter gray of the putamen.
We will see
this pattern in several sections.
Lateral
to the putamen you
can see
a clear sheet of white matter, the external
capsule. Lateral to that is a triangular island of
gray, the claustrum.
Another new gray region can be see
below the septum pellucidum.
This is the septal
region. Those rational
neuroanatomists have struck again.