Nerves are actually made up of many of the axons of individual nerve cells running together towards the spinal cord to enter into the central nervous system. Pain nerves mix with position sense nerves, temperature sense nerves, vibratory sense nerves, and muscle control nerves. These nerves become larger and are made up of more axons as they move closer to the spinal cord. Just before they reach the spinal cord the nerves form a nerve root, which splits into a front and back part (Dorsal Root). The part that goes to the back of the spinal cord carries the pain signal to the spinal cord (Dorsal Horn of the Spinal Cord). From here it is passed from a relatively short nerve (Interneuron) to the nerve tract that runs to the brain (Spinothalamic Tract). When it reaches the brain it is passed to other nerve cells that carry it over to the thinking (Cerebrum) and emotional (Limbic System) centers of the brain.