The elbow is made by the distal end of the humerus and the proximal end of two smaller bones forming the lower arm, the radius on the outer side, and the ulna on the inner side. These bones allow for the twisting movement of the hand. At the elbow the humerus ends with two processes, the medial and lateral epicondyles that can be felt on each side of the elbow. The head of the radius or radial head is a round concave area, which allows the movement around the opposed end of the humerus (capitellum), whereas the coronoid is the corresponding area of the ulna facing the distal humeral extremity, the trochlea.