Elbow

This joint complex includes three bones, the humerus (arm bone), and the radius and ulna (two bones in the forearm). Motion at this joint includes flexion (biceps), extension (triceps) and rotation (supination/pronation). The ulnar collateral ligament (UCL) attaches the humerus to the ulna, the radial collateral ligament (RCL) attaches the radius to the humerus and the annular ligament attaches the radius to the ulna.