Anatomy of the Shoulder

The end of the scapula, called the glenoid, meets the head of the humerus to form a glenohumeral cavity that acts as a flexible ball-and-socket joint.

The joint is stabilized by a ring of fibrous cartilage surrounding the glenoid called the labrum.

Ligaments connect the bones of the shoulder, and tendons join the bones to surrounding muscles. The biceps tendon attaches the biceps muscle to the shoulder and helps to stabilize the joint.

Four short muscles originate on the scapula and pass around the shoulder where their tendons fuse together to form the rotator cuff. (Get the FAQs on rotator cuff tears).

All of these components of your shoulder, along with the muscles of your upper body, work together to manage the stress your shoulder receives as you extend, flex, lift and throw.