The nervous system is anatomically and functionally divided into two parts. Inside the skull and vertebrae are the organs of the central nervous system (CNS), the brain and spinal cord. They are the body's command and control center. A complex network of nerves makes up the peripheral nervous system (PNS). Inside the cable-like nerves are bundles of elongated nerve cells or nerve fibers. These information pipelines allow the brain and spinal cord to communicate with the body's tissues, glands, and organs.