What is known as the rotator cuff is made up of a set of muscles which starts from the scapula and their respective tendons running from the humeral head (greater tubercle and the lesser tubercle). The four muscles which make up this structure are the subscapularis, the supraspinatus, the infraspinatus and the teres minor. The functions of these four muscles are to rotate the humerus, compress the humeral head within the glenoid fossa such that they help stabilise the joint and provide muscular balance to the shoulder. The tendon pertaining to the long head of the biceps is inserted into the supraglenoid tubercle of the scapula. This passes between the supraspinatus and subscapularis muscles meaning that from a functional point of view it should be considered part of the rotator cuff.