The shoulder has the greatest range of motion, responsible for lifting and for getting your hand in the right position for any task from lifting groceries, driving and dressing, to swimming and hitting the tennis ball. The shoulder can be easily injured and become unstable because of the large range of its motion and the shoulder socket is shallow. Shoulder pain can be localized or can radiate to other parts of the body, including the arms, chest and back.
Your shoulder is formed by three bones that make up two major joints:
- the humerus or arm
- the scapula or shoulder blade
- the clavicle or the collarbone
The shoulder joint is surrounded by tendons, ligaments and muscles that support it and these soft tissues can become damaged from overuse or underuse, from accidents and from conditions that cause gradual deterioration such as arthritis, bursitis and tendinitis.
These three bones form two major joints:
- the shoulder joint or glenohumeral
- the AC or acromioclavicular joint
The joints allow your arm to rotate in a full circle and elevate it upward, downward, forward and backward and more. Each joint is surrounded by cartilage to pad the meeting of the bones, ligaments that connect the bones and muscles, and the tendons attach the muscles to the bones.
Injuries such as a joint shoulder dislocation and separation, a broken collarbone, a frozen shoulder, fractures in the upper arm bone or shoulder blade, and torn tendons as in rotator cuff tears can cause severe pain and immobilize your shoulder.