Definitions for "Mesencephalon"
The middle segment of the brain; the midbrain. Sometimes abbreviated to mesen. See Brain.
The mesencephalon is the part of the brain lying between the forebrain and hindbrain. The trochlear and oculomotor nerves arise in the mesencephalon, and it contains structures important in the visual and auditory pathways, as well as other structures. The embryonic mesencephalon develops into the adult mesencephalon.
midbrain (More? Neural Notes)