Exclusive of the shoulder muscles, the human arm has 23 muscles or teamed muscle groups. These are loosely grouped according to their position in the arm – upper or lower, anterior or posterior – and by their function.
The anterior component of the upper arm contains the biceps, coracobrachialis and brachialis muscles. Together, these flex the arm at the shoulder and elbow. The posterior component holds the triceps, which are antagonistic to the anterior muscles. The lower arm holds muscles that flex, abduct and supinate the hand, as well as many of the relatively small muscles and tendons that control individual fingers.