Left cavernous sinus. The anterior genu of the cavernous ICA has been gently retracted forward to show the superior compartment of the cavernous sinus. This compartment contains the interclinoidal ligament and the oculomotor nerve . The interclinoidal ligament runs from the anterior to the posterior clinoid, and separates the clinoidal triangle (supero-medial) from the oculomotor triangle (infero-lateral). The clinoidal triangle is at the roof of the cavernous sinus and contains the clinoidal segment of the ICA. The oculomotor triangle is at the superior compartment and contains the oculomotor nerve, which at this level is protected by the inferior dural layer of the oculomotor triangle and by the extension of CSF in between the 2 dural layers of the oculomotor triangle (“extension of the oculomotor cistern”). (Image courtesy of JC Fernandez-Miranda)