Right lateral view of cavernous sinus, trigeminal nerve, and sella. The cerebrum has been dissected away and the brainstem preserved in situ in this specimen. The left olfactory bulb and tract can be seen emerging from behind the crista galli in the anterior cranial fossa. The anterior petroclinoid ligament extends from the anterior clinoid process of the lesser wing of sphenoid to the petrous apex of the temporal bone and is part of the tentorium cerebelli. The anterior portion of the midbrain is shown near the left border of the image. The right oculomotor (CNIII) nerve can be seen leaving the ventral midbrain, passing through the interpeduncular fossa toward the lateral wall of the cavernous sinus. In its course it passes caudal to the posterior cerebral artery, between this and the superior cerebellar artery, both branches of the midline basilar artery. It penetrates the dura between the anterior and posterior petroclinoid ligaments lateral to and in front of the posterior clinoid process. The right trochlear (CNIV) nerve leaves the dorsal surface of the midbrain and curves around the cerebral peduncle to also gain the lateral wall of the cavernous sinus. Both the oculomotor and trochlear nerves subsequently pass through the superior orbital fissure to the orbit. Ventral to the midbrain is the body of the sphenoid featuring the sella turcica, the midline depression containing the pituitary gland and distal pituitary stalk through the opening of the diaphragma sellae. The sella is bounded anteriorly by the tuberculum sellae and posteriorly by the dorsum sellae and its posterior clinoid processes. In this view, medial to the anterior clinoid processes are the optic nerves (CNII) emerging from the optic canals and the supraclinoid internal carotid arteries. The middle cranial fossa is the lateral depression between the lesser wing of the sphenoid and petrous portion of the temporal bone. The dura mater has been stripped to reveal the trigeminal ganglion and its three divisions: ophthalmic (CNV1), maxillary (CNV2), and mandibular (CNV3) coursing toward their openings of exit; superior orbital fissure, foramen rotundum, and foramen ovale, respectively. The ganglion lies in Meckel's cave on the trigeminal depression near the petrous apex. (Image courtesy of PA Rubino)