Cerebellum "microzones" or "microcompartments". The cerebellum is located in the posterior cranial fossa. The fourth ventricle, pons and medulla are in front of the cerebellum. It is separated from the overlying cerebrum by a layer of leathery dura mater, the tentorium cerebelli; all of its connections with other parts of the brain travel through the pons. Anatomists classify the cerebellum as part of the metencephalon, which also includes the pons; the metencephalon is the upper part of the rhombencephalon or "hindbrain". Like the cerebral cortex, the cerebellum is divided into two hemispheres; it also contains a narrow midline zone (the vermis).
Anatomy of the cerebellum posterior inferior portion of the cerebellum, the inferior cerebellar peduncle, the nucleus ambiguus, the vagus motor nucleus, the spinal trigeminal nucleus, the solitary nucleus, and the vestibulocochlear nuclei. There is considerable variation in the size and shape of the cerebellum in different vertebrate species. It is generally largest in cartilaginous and bony fish, birds, and mammals, but somewhat smaller in reptiles. The large paired and convoluted lobes found in humans are typical of mammals, but the cerebellum is generally a single median lobe in other groups, and is either smooth or only slightly grooved. In mammals, the neocerebellum is the