Lateral Perspective of Dissected Midbrain. The quadrigeminal plate, or tectum, consists of the paired superior and inferior colliculi.  Anterior to the quadrigeminal plate is the cerebral aqueduct, and superior to the quadrigeminal plate is the midline pineal gland.  The oculomotor and trochlear nerves are seen projecting from the ventral and dorsal surfaces of the midbrain, respectively.  The red nucleus has been dissected and is located within the midbrain tegmentum at the level of the superior colliculus.  The medial geniculate nucleus, a thalamic relay nucleus of the CNS auditory pathway, is seen protruding from the inferior surface of the pulvinar at the diencephalon/midbrain junction.  (Image courtesy of AL Rhoton, Jr.)