Coronal section of the skull base through the orbital apex and soft palate with view of the posterior fossa through the clivus. The foramina of the skull base anterior to the cavernous sinus include the foramen rotundum, through which V2 passes, and foramen ovale through which V3 passes. The accessory meningeal artery is of variable origin, most commonly arising from the maxillary artery and traversing foramen ovale to supply the dura. The Vidian canal lies medially to both of these foramina and shuttles the Vidian nerve (containing fibers from the greater superficial petrosal nerve and the deep petrosal nerves) and Vidian artery to the pterygopalatine fossa. The Eustachian tubes connect the nasopharynx to the middle ear and run from a posterolateral to an anteromedial direction. After the clivus has been removed, the ventral posterior fossa is exposed. Cranial nerve VI ascends from the medial pontomedullary junction to Dorello’s canal, through the cavernous sinus and to the orbital apex. (Image courtesy of AL Rhoton, Jr.)