It is possible to do more movements with the arm than with any other part of the body. The arm is such a useful tool that it’s a pity that there are only two of them! The bones that make up the arm include the humerus, in the upper arm, and the two bones of the forearm, the radius and ulna, as well as the little bones of the wrist, hand and fingers. The arm is very special as it enables the hand to get into all sorts of useful positions. The shoulder joint in particular, being a universal joint, has a huge range of movement. The hand can go above the head, behind the back and even across to scratch behind the other shoulder. The elbow works like a hinge joint allowing the hand to come nearer or go further away from the body. The elbow and wrist combined allow manipulation of the hand through more than 180 degrees i.e. from palm up to palm down, the wrist helps with grip, whilst the joints in the hand, thumb and fingers allow the dexterity of finger movement.