Here the brain has been bent to
expose the area between the cerebral and
cerebellar cortecies. You can
clearly see the dorsal surface of the midbrain.
The two large bumps are the superior
colliculi (hills). The superior colliculi are
located above (superior to) the inferior
colliculi along the brain stem.
Those logical neuroanatomists have struck again.
In the crease just caudal to the
inferior colliculi on either
side of the brain you can see a small
whitish nub. The trochlear nerve
(IV) exits
the brain stem here.
This is the only cranial nerve that exits
the dorsal surface
of the brain. You'll see this nerve more
clearly in a later view.