Endoscopic anterior view of the sellar region and left internal carotid artery and cavernous sinus. The pituitary gland rests within the sella turcica and is enclosed by dura mater containing intercavernous sinuses. The lacerum,  cavernous, and clinoid segments of the internal carotid artery are exposed here. The petrous carotid terminates in the lacerum segment shortly after turning superiorly out of the carotid canal. The cavernous carotid is a continuation of the lacerum segment and has a posterior genu in the posterior cavernous sinus and an anterior genu immediately prior to entering the proximal dural ring to become the clinoidal segment. At the distal dural ring, the clinoid segment continues as the supraclinoid or ophthalmic segment. The carotid sympathetic plexus is visible as a perivascular plexus on the surface of the internal carotid artery. McConnell’s capsular arteries typically arise from the cavernous segment and are divided into anterior and inferior capsular arteries, which supply the sella dura mater and the anterior pituitary capsule. The oculomotor (CNIII), trochlear (CNIV), ophthalmic (CNV1), maxillary (CNV2), and abducens (CNVI) nerves traverse the cavernous sinus. In the suprasellar region, the optic chiasm can be seen in close proximity with the ophthalmic artery. This artery, a branch off the supraclinoid segment of the internal carotid artery, courses with the optic nerve through the optic canal to the orbit. The anterior cerebral arteries, terminal branches of the internal carotid arteries, are just visible at the top of the image entering the interhemispheric fissure. (Image courtesy of AL Rhoton, Jr.)