set in vibration and the vibrations being transmitted along its length. Stimulation is produced by physical injury, by chemical influence, by electricity, by heat, and the message is always referred to the nerve termination. Thus, if the nerve at the elbow, over the "crazy bone," is touched, a tingling is felt in the fingers rather than at the point of pressure. A person who has had an arm or leg amputated will frequently speak of his fingers or toes on that side being cold, or complain of pain in them, because the scar below the point of amputation tightens around the nerves and pinches them.
It is through the nerves that people get in touch with the outer world and that they judge of size, weight, etc. All careful adjustment of the muscles is under the control of the nervous system.
