MIDBRAIN
• The midbrain (also known as the mescephalon) is the narrow
part of the brain that passes through the tentorial notch and
acts as a conduit between the forebrain and the hindbrain.
• It is about 0.8 inch (2cm) in length and the most superior of
the three regions of the brain stem.
• The midbrain is traversed by a narrow channel called
cerebral aqueduct ,filled with CSF, connecting the 3rd and 4th
ventricles. It is surrounded by a region called Periaqueductal
Gray Matter
• The midbrain mainly functions to regulate our movements and
helps orient our eyes and bodies to both visual and auditory
information in the world.
• It is housed by two cranial nerves which are;
I. The oculomotor nerve (CNIII)
II. The trochlear nerve (CN IV)
RELATIONS
• Laterally:
Parahippocampal gyri, Optic tracts, Posterior
cerebral artery, Basal vein, Trochlear nerve and
Geniculate bodies.
• Posteriorly
To the splenium of corpus callosum, great cerebral
vein, pineal body, posterior ends of the right and
left thalami
• Anteriorly
we have interpeduncular structures