The metencephalon is a developmental categorization of portions of the central nervous system. The metencephalon is composed of the pons and the cerebellum; contains a portion of the fourth ventricle; and the trigeminal nerve (CN V), abducens nerve (CN VI), facial nerve (CN VII), and a portion of the vestibulocochlear nerve (CN VIII). The metencephalon develops from the hindbrain, and is differentiated from the myelencephalon in the embryo by approximately 5 weeks of age. By the third month, th… (More on Metencephalon)