The peripheral nervous system consists of all the neural tissue in the body outside of the brain and spinal cord including cranial nerves and spinal nerves. There are twelve pairs of cranial nerves that come from the brain. Eleven pairs go to different organs in the head and one pair goes to the heart and abdominal cavity. Spinal nerves are the thirty one pairs of nerves originating from the spinal cord. It carries messages to and from the central nervous system. The peripheral nervous system is divided into two functional networks, the autonomic nervous system and the somatic nervous system.