Shoulder pain is so common that even Dr. Oz can't escape it! Our shoulders are prone to overuse injuries because we use our shoulders to move our arms, and we use our arms for so many tasks.
What does the shoulder look like?
A long rod-shaped bone called the humerus forms the upper arm. An umbrella-shaped structure called the acromion hovers over the humerus without touching it. The acromion is the bone that you feel when you press directly on top of your shoulder. It connects to your collarbone in front and it extends into the shoulder blade in back.
Because the humerus and the acromion don't touch, several muscles and ligaments help stabilize these two bones in place. Without these supporting structures, gravity would pull the arm bone (the humerus) right out of its socket.
When you move your arm, four different muscles keep your arm from spiraling out. These muscles form the "rotator cuff." One of these muscles, the supraspinatus, helps to stabilize the shoulder during overhead activities. Whether you are reaching for a glass in an overhead cabinet or throwing a ball to your child, you need the supraspinatus muscle to help lift your arm up.
The shoulder has its own insulation. A fluid-filled cushion, called a bursa, pads the space between the arm bone, the supraspinatus, and the acromion above.
What causes shoulder pain?
As we get older, these structures can break down. The acromion may become rough and coarse. When you lift your arm, you bring the humerus closer to the acromion. The jagged acromion can saw away at the bursa caught in between. If the pain starts when you lift your arm, and improves when you bring your arm down, it might be because the acromion is irritating the bursa and the supraspinatus muscle. This is called impingement syndrome. When the bursa gets inflamed, it's called bursitis.
If there's not much space between the acromion and the arm bone, the acromion can actually cut into the supraspinatus muscle or tendon and tear it apart. If it's partially torn, you might feel pain and weakness, but you can still do overhead activities. If it's completely torn, you might not have the strength to lift your arm overhead. The supraspinatus has been severed and can no longer lift the arm bone. Because the supraspinatus is part of the rotator cuff, both types of tears are known as "rotator cuff tears."