Anatomy

• The "ball" of the ball and socket joint in the shoulder is the upper end of the humerus. This moves within a socket of the shoulder blade called the glenoid. Four muscles called rotator cuffs allow movement of the arm and stabilize the shoulder. Other ligaments also stabilize the shoulder.
  
  

Function

• The muscles and the ball and socket joint of the shoulder provide a wide range of movement. Our ability to raise our arms over our head, swing our arms back and forth, and to stretch our arms behind us are all due to the anatomy of this joint. The ball and socket arrangement gives a greater range of motion than a hinge type joint like the knee.
  
  

Problems

• The shoulder's range of motion is due to flexibility of the muscles and ligaments. However, these muscles and ligaments can be overstretched or torn leading to weakness and pain. The bones themselves can also develop arthritis or bone spurs that can also cause pain and a grinding sensation in the joint.
  
  

Solution

• At the extreme end of the spectrum, the shoulder can be surgically replaced. Other treatment options your doctor will recommend include resting the joint if a tear is suspected, attending physical therapy to restore strength in the shoulder, or taking an anti-inflammatory for pain.
  
  

Prevention

• By caring for your shoulder you can prevent future problems that may require surgery. Avoid over-extending the shoulders in stretches and exercises to prevent tears in the muscles and ligaments. Do exercises specifically meant to strengthen the shoulder with light weights or bands. Also, try to avoid repetitive motions that can cause wear on the bones of the shoulder.