The hindbrain or rhombencephalon is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes. The hindbrain can be subdivided in a variable number of transversal swellings called rhombomeres. In the human embryo eight rhombomeres bad can be distinguished, from caudal to rostral: Rh8-Rh1. Rostrally, the isthmus demarcates the boundary with the midbrain.