Shoulder Structure

The shoulder has two main bones called the humerus (upper arm bone) and the scapula (shoulder blade).

The end of the scapula, the glenoid, refers to depression of the scapula entering into the formation of the shoulder joint.

The shoulder joint is a ball-and-socket joint between the glenoid fossa of the scapula and the head of the humerus.

Articular cartilage cushions this joint by covering the head of the humerus and face of the glenoid. Stabilizing the joint is the labrum, a ring of fibrous cartilage surrounding the glenoid.

The acromion (highest point of the shoulder) is formed by the outer end of the scapula extending over the shoulder joint. This is also called the acromial process. The acromioclavicular joint (AC joint) is the joint between the acromion of the scapula and the clavicle.

The shoulder bones are connected by ligaments (bands of tough fibrous tissue) and the bones are connected to the surrounding muscles by tendons.

Two major tendons of the shoulder are the biceps tendon, which attaches the biceps muscle to the shoulder, and the supraspinatus tendon, which helps form the rotator cuff.