Medial surface of the left hemisphere and brainstem. Identification of the cerebral peduncle gray matter nuclei: red nucleus, with oval shape, extending from the subthalamic region to the inferior third of the peduncle. At the union of the anterior one-third with the posterior two-thirds this nucleus is narrowed by the Meynert’s retroreflexus fasciculus (Meynert Fas.). On the dorsal surface, from inside to outside: oculomotor nucleus, medial longitudinal fasciculus, and reticular formation. (Image courtesy of E de Oliveira)