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What is the rotator cuff and what does it do?

The rotator cuff is a group of muscles of the shoulder joint, keeping the head of your upper arm bone (humerus) firmly within the shallow socket of the shoulder. The rotator cuff includes four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles and their tendons provide stability to the shoulder joint and allow for a wide range of motion, including lifting and rotating your arm.


Each of the rotator cuff muscles starts on the shoulder blade (scapula) and extends out to attach to the head of the humerus (upper arm bone). Here's a brief overview of their primary functions and anatomy:


1. Supraspinatus: This muscle helps with the abduction of the arm, especially the first 30 degrees of abduction (lifting it away from the body) and is situated at the top of the shoulder blade. The supraspinatus originates above the spine of the scapula in the supraspinous fossa and inserts into the greater tubercle of the humerus. 

2. Infraspinatus: Located on the back of the shoulder blade, this muscle assists in the external rotation and abduction of the humerus. It originates from the Infraspinous fossa and inserts at the greater tubercle of the humerus. 

3. Teres Minor: Similar to the infraspinatus, the teres minor muscle aids in externally rotating the arm and abduction (talking the arm out to the side) and is found just below the infraspinatus. It originates from the posterior aspect of the superior hand of the lateral border of the scapula and inserts at the greater tubercle of the humerus. 

4. Subscapularis: This muscle sits at the front of the shoulder blade and helps in the internal rotation of the arm  and helps to adduct the arm and extend it in certain positions as well as keeping the humeral head in the glenoid fossa (the socket of the shoulder ball and socket joint) and stopping it from dislocating.

All together these muscles keep the humeral head in the socket especially when moving the arm above the head. So having strength in these muscles is crucial in preventing injury and especially dislocation of the joint.  

The rotator cuff is crucial for many daily activities and sports that involve arm movements. Injuries to the rotator cuff, such as tears or strains, can lead to pain, weakness, and reduced range of motion in the shoulder.

Rotator cuff injuries are common, especially in activities requiring repetitive arm movements or heavy lifting, and can range from mild inflammation to complete tears. Here are some of the most common types of rotator cuff injuries:


1. Rotator Cuff Tears: This can be a partial tear, where the tendon is damaged but not completely severed, or a full-thickness tear, where the tendon is completely split into two parts or detached from the bone. Tears can result from acute injury or degenerative changes over time.

2. Tendinitis: Rotator cuff tendinitis refers to the inflammation of the tendons of the rotator cuff. This condition is often due to overuse of the shoulder, leading to irritation and inflammation of the tendons.

3. Impingement Syndrome: This occurs when the rotator cuff tendons are compressed or "impinged" during shoulder movements, causing pain and inflammation. Over time, this can lead to a thinning or tearing of the tendon. It's often the result of repetitive overhead activity.

4. Bursitis: The shoulder joint contains small, fluid-filled sacs called bursae that reduce friction between the joint structures. Inflammation of these bursae, known as bursitis, can cause significant pain and is often associated with rotator cuff injuries.

5. Calcific Tendinitis: This condition involves the formation of calcium deposits within the rotator cuff tendons, which can cause acute or chronic pain. It's not entirely understood why these calcium deposits form, but they can lead to significant discomfort and limited movement.

6. Frozen Shoulder (Adhesive Capsulitis): While not a direct injury to the rotator cuff tendons, frozen shoulder is a condition that leads to stiffness and restricted range of motion in the shoulder. It can occur as a result of rotator cuff injuries that lead to disuse of the shoulder due to pain.

Symptoms of rotator cuff injuries can include pain at rest and at night, particularly if lying on the affected shoulder, pain when lifting and lowering the arm or with specific movements, weakness when lifting or rotating the arm, and a crackling sensation when moving the shoulder in certain positions.

Treatment varies based on the severity of the injury, ranging from rest, ice, and physical therapy to strengthen and improve flexibility, to anti-inflammatory medications, steroid injections, and in more severe cases, surgery to repair the torn tendon. Early diagnosis and treatment are important to prevent further damage and ensure the best possible outcome.


Treatment for rotator cuff injuries varies depending on the severity and can range from remedial massage, myotherapy, dry needling, exercise and modifying lifestyle activities that may be aggravating the shoulder. Short term anti-inflammatory medications may be advised surgery in more severe cases.

If you are having shoulder issues then having a detailed assessment and treatment is essential at getting you out of pain fast and keeping you that way.


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