Central nervous system

The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord.

The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—that is, all multicellular animals except sponges and jellyfish.

It is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain.

Not all animals with a central nervous system have a brain, although the large majority do.

The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals.