There are five major muslces of the shoulder joint that are responsible for the movement of the shoulder. In the front portion of the shoulder, originating from the scapula, the muscles involved are the subscapularis muscle and the biceps muscles (Figure 3). The supraspinatus is a relatively small muscle that runs from the top portion of the scapula which inserts into the top of the humeral head. From that back position, the muscles of the shoulder joint include the infraspinatus muscle and the teres minor muslces (Figure 3). These muscles of the shoulder combine to form a thick cuff that is important in stabilizing the shoulder as well as elevating and rotating the arm. Elevation of the arm causes squeezing of the bursa located above the supraspinatus tendon and the acromion.