Brachialis tendons attach to coranoid processes. Flexor digitorum profundus muscles arise from ulnas' proximal two-thirds. Pronator quadratus muscles arise from lines on ulnas' distal one-quarters. Triceps brachiis' three heads combine into common tendons that attach to ulnas' olecranon processes. Anconeus tendons attach to ulnas' proximal one-fifths.
Supinator muscles arise from medial surfaces of ulnas' proximal ends.
Elbow joint movements involve ulna movements relative to humeruses. Kinesiologists generally include forearm joint actions with elbow joint actions. However, muscles that attach to radiuses can only indirectly influence ulna movements. Therefore, I separte forearm and elbow joint actions. Ulnas only move toward or away from humerus' anterior surfaces.