Lateral view of right cavernous sinus. Portions of the petrous temporal and sphenoid bones have been drilled away to provide greater exposure of structures. Here, the right internal carotid artery has emerged from the carotid canal and occupies the cavernous sinus adjacent to the body of the sphenoid bone. Several nerves are related to this artery. Within the lateral wall of the sinus, arranged from superior to inferior, are the oculomotor, trochlear (not present), ophthalmic, and maxillary nerves. The abducens nerve courses on the lateral surface of the ICA within the cavernous sinus. The distal dural ring marks the junction of the intradural and extradural portions of the artery. The mesencephalon and pons are shown on the left side of the image. On the anterior pons is the basilar artery with its pontine branches, the superior cerebellar arteries, and the terminal posterior cerebral arteries. The oculomotor nerves emerge from the mesencephalon and course between the superior cerebellar and posterior cerebral arteries. The posterior communicating arteries connect the vertebrobasilar system with the internal carotid arteries. The optic nerves are shown entering the optic canals to the orbits and the mandibular nerve descends through foramen ovale to enter the infratemporal fossa. Posteriorly, the roof of the internal auditory canal has been drilled to reveal the facial nerve, the geniculate ganglion, and the greater superficial petrosal nerve. The latter courses deep to the trigeminal ganglion towards the pterygoid canal. It joins the deep petrosal nerve (consisting of postganglionic sympathetic fibers) to form the Vidian nerve and provides preganglionic parasympathetic fibers to the pterygopalatine ganglion. (Image courtesy of PA Rubino)