Removal of the gray matter of the hypothalamus exposes some of the periventricular fibers coursing from the hypothalamic area toward the mesencephalon. Lateral to these, in the depths of the dissection, the column of the fornix (6) is seen as it approaches the mammillary body and the mammillothalamic tract (8) as it leaves. The dissected area (3) of the thalamus contains longitudinally coursing fibers of the internal medullary lamina. More posteriorly, fine fibers are found medial to the position of the fasciculus retroflexus (uncovered in a later dissection). Fibers of the third nerve (32) are exposed within the tegmentum of the mesencephalon.