Nerves are the “telephone wiring” system that carries messages from the brain to the rest of the body. A nerve is like a telephone cable wrapped in insulation. An outer layer of tissue forms a cover to protect the nerve, just like the insulation surrounding a telephone cable (see Figure 1). A nerve contains millions of individual fibers grouped in bundles within the “insulated cable.”
Nerves serve as the “wires” of the body that carry information to and from the brain. Motor nerves carry messages from the brain to muscles to make the body move. Sensory nerves carry messages to the brain from different parts of the body to signal pain, pressure, and temperature. While the individual axon (nerve fiber) carries only one type of message, either motor or sensory, most nerves in the body are made up of both.