Transsylvian Exposure of the Parasellar and Paraclival Region. The internal carotid artery terminates by bifurcating into the anterior cerebral artery (A1) and middle cerebral artery (M1). The olfactory nerve, optic nerve/chiasm, and oculomotor nerve are visible within the transsylvian corridor. The oculomotor nerve is visible inferior to the posterior cerebral artery within the deep margin of the corridor. (Image courtesy of AL Rhoton, Jr.)