The Shoulder Joint

The parts of the joint

The shoulder joint is where the humerus (upper arm bone) meets the scapula (shoulder blade):

• Muscles and ligaments help make up the joint. They attach to the shoulder blade and upper arm bone.

• At the top of the shoulder blade are two bony knobs called the acromion and coracoid process.

• The subacromial space is between the top of the humerus and the acromion. This space is filled with tendons, muscles, and the subacromial bursa.

• The bursa is a sac of fluid that cushions shoulder parts as they move.

• The supraspinatus muscle and tendon are located in the subacromial space. They help form the rotator cuff and are commonly injured in a rotator cuff tear.

• The rotator cuff is a group of muscles and tendons that surround the shoulder joint. These muscles and tendons hold the arm in its joint. They also help the shoulder move and rotate.