SHOULDER ASSESSMENT SERIES PART 4: PAINFUL ARC SYNDROME The Painful Arc Syndrome is pain during 60° until 120° of abduction. The reason for this is that the anterior and posterior parts of the deltoid muscle start to become abductors from 60° of abduction on due to the position of the humerus and its axis of motion. If the rotator cuff muscles are not strong enough or cannot control to counteract the abduction force of the deltoids, the deltoids will translate the humeral head cranially and caus