The Shoulder Joint

The Shoulder Joint (Glenohumeral Joint)

Shoulder Joint Function

The shoulder is one of the largest and most complex joints in the body. The shoulder is formed where the humerus (upper arm bone) fits into the scapula (shoulder blade). The shoulder joint is a ball and socket type of joint which allows for a range of motions in the shoulder, such as the upward elevation of the arm and its extension, as well as internal and external motion


Other important bones in the shoulder include:

- The acromion which is a boney projection off the scapula

- The clavicle (collarbone) which joins the acromion in the acromioclavicular joint

The shoulder has several other important structures:

- The rotator cuff is a collection of muscles and tendons that surround the shoulder, giving it support and allowing a wide range of motion

- The bursa is a small sac of synovial fluid that cushions and protects the various joints

- The labrum is a cuff of cartilage that forms a cup for the ball-like head of the humerus to fit into

- The humerus fits relatively loosely into the shoulder joint, which gives the shoulder a wide range of motion, but also makes it vulnerable to injury

 Common Injuries of the Shoulder Joint

Frozen shoulder – inflammation develops in the shoulder that causes pain and stiffness

Osteoarthritis – the common “wear and tear” arthritis that occurs with aging

Rheumatoid arthritis – a form of arthritis in which the immune system attacks the joints, causing inflammation and pain

Rotator cuff tear – a tear in one of the muscles or tendons surrounding the top of the humerus

Shoulder impingement – the acromion presses on the rotator cuff as the arm is lifted

Shoulder dislocation – the humerus or one of the other bones in the shoulder slips out of position

Shoulder tendonitis – inflammation of one of the tendons in the shoulder’s rotator cuff

Shoulder bursitis – inflammation of the bursa sac of synovial fluid in the joints

Labral tear – a tear in the labrum of the cuff of cartilage that overlies the head of the humerus

Shoulder Treatments

Physical therapy – an exercise program can strengthen shoulder muscle and improve flexibility

Pain relievers – OTC medications or prescription medications

RICE therapy – Rest, Ice, Compression, and Elevation

Corticosteroid injections – reduce the pain and inflammation caused by bursitis or arthritis

Nutritional Supplements – can assist to restore function

Shoulder surgery – generally performed to help make the shoulder joint more stable