Nervous system, central (CNS): That part of the nervous system that consists of the brain and spinal cord.
The central nervous system (CNS) is one of the two major divisions of the nervous system. The other is the peripheral nervous system (PNS), that part of the nervous system that lies outside the brain and spinal cord.
The peripheral nervous system (PNS) connects the central nervous system (CNS) to sensory organs (such as the eye and ear), other organs of the body, muscles, blood vessels and glands. The peripheral nerves include the 12 cranial nerves, the spinal nerves and roots, and what are called the autonomic nerves that are concerned specifically with the regulation of the heart muscle, the muscles in blood vessel walls, and glands.