Sagittal Perspective of Cerebellar Lobules. The cerebellum is divided into 10 lobules designated by Roman numerals I through X.  Lobules I and II are small and confined to the vermis.  Lobule X is synonymous with the flocculonodular lobe. The remainder of the lobules (III thru IX) contain portions of both the cerebellar vermis and cerebellar hemisphere. The perfusion zones of the superior cerebellar artery and posterior inferior cerebellar arteries are well visualized in this image. (Image courtesy of AL Rhoton, Jr.)