Peripheral nervous system (pns):
Except for the brain and the spinal cord, the rest of the network of nerves and neurons is included in tha peripheral nervous system, or PNS for short. This system links the brain andspinal cord to the rest of the body. Any message that is sent to the brain or from it to the rest of body, travels along the peripheral nerves. The PNS consists of 12 pairs of individual nerves called cranial nerves, originating from the brain hence called cranical nerves (from cranium, the skull) and the 31 pairs of spinal nerves that branch off from the spinal cord. Each spinal nerve splits into three components soon after leaving the spinal cord. One- branch passes to the skin and muscles of the front of the body; a second branch leads to the skin and muscles of the back; the third branch reaches the internal organs. The first two branches carry sensory information to the brain, and carry motor signals from the brain to the muscles and glands. The third branch forms the "autowmic system" which governs actions of the internal organs that are mostly involuntary. If you look at Fig. again, you would be able to appreciate the vast network of nerves that make up the peripheral nervous system.