PNS (peripheral nervous system): That portion of the nervous system that is outside the brain and spinal cord. The peripheral nervous system (PNS) is one of the two major divisions of the nervous system.The other is the central nervous system (CNS) which is made up of the brain and spinal cord.The nerves in the peripheral nervous system (PNS) connect the central nervous system (CNS) to sensory organs (such as the eye and ear), other organs of the body, muscles, blood vessels and glands.NS (peripheral nervous system): That portion of the nervous system that is outside the brain and spinal cord. The peripheral nervous system (PNS) is one of the two major divisions of the nervous system.