A typical muscle is thick in the middle and tapers gradually towards the ends. It is the ends of a muscle that are attached to bones. One end of a muscle is anchored to a bone that the muscle cannot move. This attachment is called the origin of the muscle. The other end is attached to a bone that the muscle is intended to move. This attachment is called the insertion of the muscles. For example, the muscle at the front of the upper arm called the biceps has its origin at the shoulder bone,and its insertion is just below the elbow joint on the bone that is on the thumb side of the forearm. The actual attachment of the end of a muscle to a bone is usually accomplish by a short, tough cord of much the same kind of tissue that makes up ligaments. This connective cord is called a tendon.
All the muscles of the body and their tendons make up the muscular system of the body.
