Overview:
The rotator cuff is comprised of four muscles. These individual muscles combine at the shoulder to form a thick "cuff" over this joint. The rotator cuff has the important job of stabilizing the shoulder as well as elevating and rotating the arm. Each muscle originates on the shoulder blade, or scapula, and inserts on the arm bone, or humerus.The Four Muscles:
The four muscles that form the rotator cuff are the supraspinatus, infraspinatus, teres minor, and subscapularis. Often the mnemonic S.I.T.S is used to help remember the muscles that make up the rotator cuff.Supraspinatus:
The supraspinatus muscle originates above the spine of the scapula and inserts on the greater tuberosity of the humerus. The supraspinatus abducts, or elevates, the shoulder joint. It also works with the other rotator cuff muscles to stabilize the head of the humerus in the glenohumeral joint, or shoulder joint.Infraspinatus :
The infraspinatus muscle originates below the spine of the scapula, in the infraspinatus fossa, and inserts on the posterior aspect of the greater tuberosity of the humerus. The infraspinatus externally rotates the shoulder joint. It also works with the other rotator cuff muscles to stabilize the head of the humerus in the glenohumeral joint, or shoulder joint.Teres Minor:
The teres minor muscle originates on the lateral scapula border and inserts on the inferior aspect of the greater tuberosity of the humerus. The teres minor muscle externally rotates the shoulder joint. It also works with the other rotator cuff muscles to stabilize the head of the humerus in the glenohumeral joint, or shoulder joint.Subscapularis:
The subscapularis muscle originates on the anterior surface of the scapula, sitting directly over the ribs, and inserts on the lesser tuberosity of the humerus. The subscapularis muscle works to depress the head of the humerus allowing it to move freely in the glenohumeral joint during elevation of the arm. It also works with the other rotator cuff muscles to stabilize the head of the humerus in the glenohumeral joint, or shoulder joint.
