Superior Perspective of the Cerebellum and Brainstem. The cerebellum is divided anatomically into anterior, posterior, and flocculonodular lobes. The anterior and posterior lobes are separated by the primary (preclival) fissure. The quadrangular lobule is similarly divided into anterior and posterior portions by the preclival fissure. The superior posterior (postclival) fissure divides the posterior quadrangular lobule (also referred to as the simple lobule) from the superior semilunar lobule. The superior semilunar lobule is separated from the inferior semilunar lobule by the horizontal fissure. (Image courtesy of AL Rhoton, Jr.)