A, The right SCA arises from the basilar artery as a duplicate artery. The rostral duplicate trunk gives rise to vermian branches that supply the vermis and the adjacent part of the hemisphere. The caudal duplicate trunk gives rise to hemispheric branches. B, Enlarged view. Care is required in occluding and dividing the superior petrosal veins around the trigeminal nerve, because the branches of the SCA may be intertwined with the tributaries of the veins, as in this example. The peduncular vein, which usually empties into the basal vein, joins the lateral mesencephalic vein, and empties into the superior petrosal sinus. C, The lip of the fissure has been retracted to expose the SCA trunks and branches. D, The posterior lip of the cerebellomesencephalic fissure has been removed. Within the fissure, the SCA branches pass down the superior cerebellar peduncle. Some SCA branches pass above and some below the trochlear nerve. The SCA gives rise to a marginal branch that supplies some of the petrosal surface bordering the tentorial surface. (Images courtesy of AL Rhoton, Jr.)