These messages tell the brain where the parts of the body are, and what is happening to them. When the spinal cord is damaged, the patient is not only unable to move, but also unable to feel. He or she is in danger of being cut by sharp edges or burned by hot objects that the rest of us are readily able to detect and avoid. Nerve fibres are not arranged at random. Each nerve consists of a fibre, which is attached to a nerve cell.
Messages start in the nerve cell, and are carried down the nerve fibre.
When they reach the end of the nerve fibre they are transmitted to the next nerve cell. So the passage of messages through the nervous system is like a series of relay runners passing a baton on from one runner to the next. When a nerve is damaged, the part of the fibre which is separated from the cell body breaks down and dies. Although the nerve cell body still survives, it has lost the pathway which it needs to send information to the next cell. The ability to relay messages is lost.