Lateral view of pontomedullary junction at cerebellopontine angle. The pontomedullary sulcus separates the pons from the medulla. Anteriorly, the abducens nerve emerges from this junction. The elongate pyramid, containing corticospinal tract fibers, is visible on the anterior surface of the medulla. Posterior to the pyramid is the oval-shaped inferior olive. The anterolateral or preolivary sulcus intervenes between the pyramid and the olive. From this sulcus emerge the rootlets of the hypoglossal nerve (although not preserved in this dissection). The rootlets of the glossopharyngeal, vagus, and accessory nerves emerge in a rostro-caudal sequence from the postolivary sulcus (also not preserved in this dissection).  Tufts of choroid plexus can be seen protruding from the right lateral foramen (of Luschka) of the fourth ventricle. The posterolateral fissure separates the posterior cerebellum from the flocculus. (Image courtesy of PA Rubino)