Rheumatoid arthritis is a disease of the immune system. This is the system that protects you from infection. RA may cause pain and stiffness in your shoulder where the humerus (the bone of the upper arm) meets the shoulder socket.

This condition is a fracture of the head of the humerus - the "ball" of the shoulder's ball-and-socket.

This condition is a deformity of the spine. With it, your vertebrae change from a cylindrical shape to a wedge shape. Your spine may begin to curve forward. Eventually, this gives your upper back a rounded appearance.

Osteoarthritis, also called degenerative arthritis, is a gradual breakdown of cartilage in the joints. Cartilage is a tough, flexible connective tissue that protects the ends of bones in the joints.

Some of the muscles in your shoulder have opposing roles. When you move your arm, certain muscles contract while their opposing muscles relax. But when a muscle becomes much stronger than its opposing muscle, your shoulder can become unstable.

This condition is a traumatic fracture of the humeral head that leaves an indentation in the bone. This changes the shape of the humeral head and can interfere with normal arm motion.

This condition is a deterioration of the facet joints, which help stabilize the spine and limit excessive motion.

If you have pain in your shoulder, you may have a torn labrum. That's the thick band of tissue that goes around your shoulder socket. It helps make the socket deeper. It cushions the bone of your upper arm and keeps it from slipping.

This condition is a loss of motion or stiffness in the shoulder, usually accompanied by pain in the joint.

This condition is a break of the scapula, the large, flat, triangular bone that contains the shoulder socket. Because the scapula is well protected by the muscles of the shoulder, scapula fractures are uncommon.

This condition is a fracture of the bony bump that is located opposite of the head of the humerus. This type of fracture can interfere with the rotator cuff.

This is a fracture of a part of the shoulder blade called the "glenoid." This is the socket that holds the head of the humerus (the bone of the upper arm). A glenoid fracture can allow the head of the humerus to slip out of the socket.

This is a common shoulder injury. It's a break of the bone that rests between the shoulder blade and the sternum. We call it the "collarbone." Your collarbones help connect your arms to your body.

This painful condition occurs when calcium deposits form in tendons of the rotator cuff. These tendons and surrounding tissues in the shoulder become inflamed.

The spinal column is the body's main support structure. Its thirty-three bones, called vertebrae, are divided into five regions: cervical, thoracic, lumbar, sacral and coccygeal.

This painful condition occurs when calcium deposits form in tendons of the rotator cuff. These tendons and surrounding tissues in the shoulder become inflamed. This condition typically affects adults.

These are warm or painful sensations caused by an injury to the brachial plexus. This is a network of nerves that passes through your shoulder. They travel down your arm and to your hand.

This is a problem with a tendon in your shoulder. Most often, it's the "long head of biceps" tendon. It travels from the front of your upper arm to the top of your shoulder socket.

Tendons are strong bands of tissue that connect muscle to bone. With this injury, one of the tendons anchoring your biceps muscle is torn. It may be torn partially or completely.

The shoulder is a complex structure made of three separate joints. They work together to give the shoulder a tremendous range of motion. Let's take a closer look at the main parts of the shoulder's anatomy.