In birds, the forearm muscles supinate, pronate, flex and extend the distal wing. This confusion can arise because the forearm can pronate and supinate. When the forearm is pronated, the brachioradialis tends to supinate as it flexes. Their grip starts off with a palmar supinate grasp. Its function is to supinate the forearm. The most important of these functions is to supinate the forearm and flex the elbow.