Shoulder

SHOULDER ANATOMY

The upper extremities are connected to the chest from the shoulder, which consists of two main joints. The first is known as the glenohumeral joint, which connects the top of the shoulder blade to the beginning of the arm bone. The second shoulder joint is known as the acromioclavicular joint and it connects the shoulder blade with the collar bone. These joints allow the shoulder to move completely and function normally.

BONES IN THE SHOULDER

There are three main bones that form the shoulder — the humerus (arm bone), the clavicle (collarbone), and the scapula (shoulder blade). The scapula creates a hole for the shoulder joint which is covered by cartilage and is known as the glenoid. The glenohumeral joint is where the shoulder blade connects with the rounded top part of the humerus.

The top of the shoulder has a second joint where another part of the shoulder blade—the acromion—is joined to the collarbone. This is known as the acromioclavicular joint.

THE ROTATOR CUFF

The rotator cuff consists of a group of four tendons and muscles which are on the outside part of the glenohumeral joints. The muscle moves the bones by contracting, and the tendons attach the muscle to the bone. The muscles of the rotator cuff play a vital role in moving the ball-and-socket shoulder joint.

The rotator cuff plays an important role in different activities. It can cause severe pain upon injury. When it is irritated or inflamed, the condition is known as shoulder bursitis or rotator cuff tendonitis. A rotator cuff tear happens when its tendons are torn.

THE SHOULDER CAPSULE

The ball-and-socket of the shoulder joint is surrounded by the shoulder capsule. The capsule contains joint fluid and separates the joint from the body. The shoulder joint is kept properly in position by different ligaments which are connected to the joint capsule. The shoulder capsule ligaments are torn when there is a dislocation of the shoulder.

THE SHOULDER MUSCLES

Several people assume that the rotator cuff consists of all the muscles that surround the shoulder joint, but these include only four of the seventeen muscles that pass the shoulder joint. Most of these muscles are important for normal shoulder function. The periscapular muscles are some of the most commonly damaged when people suffer shoulder injuries.

These muscles are responsible for controlling the shoulder blade and its movement, which is important for shoulders to function normally. The shoulder joint socket is connected to the scapula. If its movement is restricted, the shoulder won’t function normally.