Midbrain tegmentum

The midbrain is anatomically delineated into the tectum (roof) and the tegmentum (floor). The midbrain tegmentum extends from the substantia nigra to the cerebral aqueduct in a horizontal section of the midbrain. It forms the floor of the midbrain that surrounds below the cerebral aqueduct as well as the floor of the fourth ventricle while the midbrain tectum forms the roof of the fourth ventricle. The tegmentum contains a collection of tracts and nuclei with movement-related, species-specific, and pain-perception functions. The general structures of midbrain tegmentum include red nucleus and the periaqueductal grey matter.

This keyword could refer to multiple things. Here are some suggestions: