Dorsal view of the midbrain and superior surface of the cerebellum. The tectum or quadrigeminal plate forms the dorsal surface of the midbrain and is composed of the paired superior and inferior colliculi. The superior (or tentorial) surface of the cerebellum is formed by the vermis in the midline and the cerebellar hemispheres on each side. The primary (or tentorial) fissure divides the superior surface into an anterior and a posterior portion. The anterior portion contains the culmen (the highest part of the vermis) and the quadrangular lobe (of hemisphere), while the posterior portion contains the declive (of vermis) and the simple lobule (of hemisphere). The postclival fissure, which is formed at the lower edge of the declive and continues laterally, divides the simple lobule from the superior semilunar lobule. The horizontal (petrosal) fissure divides the superior surface of the cerebellum from the inferior (or suboccipital) surface. The horizontal fissure also divides the superior semilunar lobule from the inferior semilunar lobule. The folium and tuber of the vermis (along with the pyramid and uvula) are located in the midline of the inferior (or suboccipital surface) of the cerebellum. The dentate nucleus is seen deep to the cerebellar white matter. The dentato-rubro-thalamic fibers form the superior cerebellar peduncle. (Image courtesy of M Nunez)