The term central nervous system refers to one of two parts of the nervous system defined on the basis of dissection. In vertebrates it is the part located within the cranial cavity and vertebral column. Classically it is divided into two parts: brain and spinal cord ( Carpenter-1983 ). It is found in the human, macaque, rat, mouse and other mammals. Functionally the CNS is divided into gray matter and white matter of the central nervous system ( Swanson-2004; see Functional CNS Model - Rat ). In both models the other part of the nervous system is the peripheral nervous system.