Endoscopic transnasal view of sellar and parasellar regions. The pituitary gland can be seen contained within the sella turcica of the sphenoid bone. Part of the lesser wing has been removed to expose the optic chiasm and optic nerves, and the interhemispheric fissure containing the anterior cerebral arteries. Portions of the petrous temporal, sphenoid, and clival bones have also been removed. This has revealed the multiple segments of the internal carotid artery: petrous, lacerum, cavernous, clinoid, and supraclinoid. The ophthalmic artery arises from the supraclinoid segment and courses with the optic nerve into the optic canal. Within the lateral wall of the cavernous sinus are the oculomotor, ophthalmic, and maxillary nerves. The oculomotor, ophthalmic, and abducens nerves converge on and traverse the superior orbital fissure to enter the orbit, while the maxillary nerve passes through the foramen rotundum to enter the pterygopalatine fossa. The abducens nerve courses within the cavernous sinus on the lateral surface of the cavernous segment of the internal carotid artery, which carries the perivascular carotid sympathetic nerve plexus. Inferior and medial to the foramen rotundum and the maxillary nerve is the Vidian canal and nerve, which also open into the pterygopalatine fossa. The basilar artery and pontine branches can be seen lying on the pons. (Image courtesy of AL Rhoton, Jr.)