The midbrain, part of the brain stem, divided in two structures: the tectum and tegmentum. The tectum (or ‘roof’) forms the dorsal surface of the midbrain, and is made up of the (posterior) inferior and (anterior) superior colliculi (the former having auditory functions, the latter visual functions). The tegmentum, lying anterior to the tectum, consists of three structures (in addition to the reticular formation): red nucleus, substantia nigra and periaqueductal grey (contains third and fourth ventricles). The mesencephalon, particularly the red nucleus and substantia nigra, plays a crucial role in the sensory control of movement. During embryogenesis, it arises from the second vesicle of the neural tube. Unlike the prosencephalon and rhombencephalon, it does not divide during the rest of neural development.
See Brain (or encephalon), Brain stem, Central nervous system (CNS), Diencephalon, Embryogenesis, Gray matter, Mesencephalic reticular activating system, Metencephalon, Neural tube, Prosencephlon, Red nucleus, Rhombencephalon, Superior colliculus, Tegmentum, Vesicles