Endoscopic view of right anteromedial aspect of petroclival area. Petrosal, sphenoidal, and clival bone have been removed to expose the internal carotid artery (ICA) (its petrous and cavernous portions) and basilar artery overlying the pons. The trigeminal nerve is shown coursing over the petrous apex to enter Meckel's cave and expands as the trigeminal (Gasserian) ganglion. From this arises the three branches or divisions of the nerve: ophthalmic (V1), maxillary (V2), and mandibular (V3). The cavernous venous sinus is shown with the abducens nerve coursing along the lateral surface of the ICA. The Vidian nerve courses along the lateral surface of the petrous portion of ICA toward its canal. The anterior inferior cerebellar artery arises from the proximal portion of the basilar artery and passes posteriorly toward the cerebellum. (Image courtesy of AL Rhoton, Jr.)