Axial Anatomic Specimen through the Midbrain

Periaqueductal Gray Around the Aqueduct of Sylvius

The anatomic section is an axial slice through the brain showing the structures of the midbrain. The most anterior structures of the midbrain are the cerebral peduncles followed by the substantia nigra, red nucleus, periaquaductal gray (PAG or central gray), aqueduct of Sylvius and finally the superior colliculus. Structures that are related to the midbrain anteriorly are the mamillary bodies and the optic tract. The hippocampus is positioned posterolaterally and the superior aspect of the cerebellum is seen posteriorly.

Courtesy Department of Anatomy and Neurobiology at Boston University School of Medicine Dr. Jennifer Luebke , and Dr. Douglas Rosene 97140b03c.9

Whole Mount of the Midbrain in Axial Projection

The mounted and stained midbrain in transverse plane illustrates the component structures. The anterior border of the midbrain incorporates the cerebral peduncles (CP), and the substantia nigra (SN). Between the substantia nigra and the aqueduct (teal arrow) is an area of the midbrain called the tegmentum (floor of the midbrain) Within the tegmentum other structures include red nuclii (RNu), oculomotor nucleus (Nu3), periaquaductal gray (PAG), and the aqueduct of Sylvius which is border forming between the tegmentum anteriorly and the tectum (roof) posteriorly. The posterior end of the midbrain is bordered by the colliculi in the tectum. Note also the paired mamillary bodies anteriorly (MB) and the medial geniculate body (MG) posterolaterally

Courtesy Department of Anatomy and Neurobiology at Boston University School of Medicine Dr. Jennifer Luebke , and Dr. Douglas Rosene 98483L.8