Lab 2 - Internal Organization of the Brain

Midbrain - Coronal, Horizontal and Sagittal Sections

Major Midbrain structures you should learn include, Cerebral Peduncles, the Interpeduncular Fossa and the Fascicles of the Oculomotor Nerve Rootlets which are exiting in the interpeduncular fossa. Also in the midbrain, find the Substantia Nigra, a thick band of cells posterior to the Cerebral Peduncles. Superior to it is the Red Nucleus, a large globular mass on either side of the midline. When you no longer see the red nucleus, the inferior colliculus begins.

The colliculi form the Tectum (roof) of the midbrain and are located posterior to the cerebral aqueduct. The gray matter surrounding the cerebral aqueduct is called the Periaqueductal Gray.

The midbrain Tegmentum extends from the substantia nigra up to the periaqueductal gray.

The Reticular Formation is a loose network of neurons that are located within the core of the midbrain tegmentum.