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The rotator cuff is a group of four muscles and tendons that stabilise the human shoulder and allow for its extensive range of motion. The four muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Together, these four tendons stabilise the upper arm bone to the shoulder socket.
| Characteristics | Values |
|---|---|
| Number of muscles | 4 |
| Names of muscles | Supraspinatus, Infraspinatus, Teres minor, Subscapularis |
| Function | Stabilises the shoulder and allows for its extensive range of motion |
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What You'll Learn
The four muscles that make up the rotator cuff
The rotator cuff is a group of muscles and tendons that stabilise the shoulder and allow for its extensive range of motion. There are four muscles that make up the rotator cuff, which are also referred to as the SITS muscles, with reference to the first letter of their names: Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis. These muscles arise from the scapula and connect to the head of the humerus, forming a cuff around the glenohumeral joint. The supraspinatus muscle spreads out in a horizontal band to insert on the superior facet of the greater tubercle of the humerus. The greater tubercle projects as the most lateral structure of the humeral head. Medial to this, in turn, is the lesser tubercle of the humeral head. The subscapularis muscle origin is divided from the remainder of the rotator cuff origins as it is deep to the scapula. The four muscles of the rotator cuff are essential players in almost every type of shoulder movement, including flexion, abduction, internal rotation and external rotation. Balanced strength and flexibility in each of these muscles are vital to maintain functioning of the entire shoulder girdle.
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The shoulder complex
The rotator cuff muscles are essential players in almost every type of shoulder movement, including flexion, abduction, internal rotation, and external rotation. Balanced strength and flexibility in each of these four muscles are vital to maintaining the functioning of the entire shoulder girdle. The cuff helps to stabilise the upper arm bone to the shoulder socket and allows for a wide range of motion in the shoulder.
The supraspinatus muscle spreads out in a horizontal band to insert on the superior facet of the greater tubercle of the humerus. The greater tubercle projects as the most lateral structure of the humeral head, with the lesser tubercle of the humeral head medial to it. The subscapularis muscle origin is divided from the remainder of the rotator cuff origins as it is deep to the scapula.
Cranial to the rotator cuff, there is a bursa which covers and protects the muscle and tendons, as they are in close contact with the surrounding bones. The rotator cuff muscles work alongside the non-contractile tissue of the glenohumeral joint (static stabilizers) such as the capsule, the labrum, the negative intraarticular pressure, and the glenohumeral ligaments; as well as the contractile tissues (dynamic stabilizers) such as the long head of the biceps brachii.
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The upper arm bone
The humerus is surrounded by the four rotator cuff muscles and their tendons: the supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles arise from the scapula and connect to the head of the humerus, forming a cuff around the glenohumeral joint. The glenohumeral joint is a ball and socket joint, with the ball being the humeral head and the socket being the glenoid fossa of the scapula. The joint is supported by ligaments and surrounded by the rotator cuff muscles.
The rotator cuff muscles are essential for almost every type of shoulder movement, including flexion, abduction, internal rotation, and external rotation. They provide strength and stability to the shoulder complex, allowing for a wide range of motion. Balanced strength and flexibility in each of the four muscles are vital to maintain the functioning of the entire shoulder girdle.
The ulnar nerve lies at the distal end of the humerus near the elbow. When struck, it can cause a tingling sensation and sometimes significant pain. This is possibly why the bone is popularly referred to as "the funny bone".
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The glenohumeral joint
The rotator cuff is made up of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles and their tendons provide strength and stability to the shoulder complex. They are also referred to as the SITS muscles, with reference to the first letter of their names.
The rotator cuff muscles arise from the scapula and connect to the head of the humerus, forming a cuff around the glenohumeral joint. The glenohumeral joint is a ball-and-socket joint, comprising a large spherical humeral head and a small glenoid cavity. This anatomy makes the joint highly mobile but also unstable.
Together, these stabilising tissues allow for a wide range of motion in the shoulder while also maintaining its stability. The rotator cuff muscles are essential players in almost every type of shoulder movement, including flexion, abduction, internal rotation, and external rotation. Balanced strength and flexibility in each of these four muscles are vital to maintain the functioning of the entire shoulder girdle.
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The scapula
The rotator cuff muscles are essential for almost every type of shoulder movement, including flexion, abduction, internal rotation, and external rotation. They provide strength and stability to the shoulder complex, allowing for the shoulder's extensive range of motion while also maintaining its stability. The scapula is also the origin of the subscapularis muscle, which is divided from the remainder of the rotator cuff origins as it is deep to the scapula.
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Frequently asked questions
There are four muscles in the rotator cuff.
The four muscles in the rotator cuff are: supraspinatus, infraspinatus, teres minor, and subscapularis.
The rotator cuff is a group of muscles and tendons that stabilise the human shoulder and allow for its extensive range of motion.
