Mesencephalon

In anatomy, the mesencephalon, also called the midbrain, is the superior section of the brainstem and is "the middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimoter systems."

The ventral tegmentum mesencephali contains the red nucleus.

Section through the midbrain.