Dissection of the right parasellar area with the dura mater removed to show structures within and on the lateral wall of the cavernous sinus. Note the superior-to-inferior relationship of the oculomotor, trochlear, ophthalmic, and maxillary nerves (OTOM) as they converge on the superior orbital fissure. Venous blood within the cavernous sinus has been removed to reveal the cavernous segment of the internal carotid artery. Note the course of the abducens nerve. After passing along the clivus, it passes beneath the petrosphenoidal ligament through Dorello's canal and then along the lateral aspect of the internal carotid artery toward the superior orbital fissure. Near the petrous apex the trigeminal nerve expands at the trigeminal (semilunar) ganglion from which arises its three divisions. The ophthalmic nerve courses through the superior orbital fissure, the maxillary nerve courses through the foramen rotundum, and the mandibular nerve courses through foramen ovale. (Image courtesy of AL Rhoton, Jr.)