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