Endoscopic endonasal superior transclival approach. Overview of the anatomy of the interpeduncular cistern using a 45 degree endoscope: basilar bifurcation, oculomotor nerves, superior cerebellar (SCA) and posterior cerebral arteries (PCA), infundibulum, floor of the third ventricle, and optic tract. Note the presence of a right fetal posterior communicating artery (PComA). The trochlear nerve and the free tentorial edge (anterior petroclinoidal ligament) form the true lateral limit of the superior tranclival approach. (Image courtesy of JC Fernandez-Miranda)