The rotator cuff is made up of four muscles that help move and stabilize the shoulder joint. Damage to any one of the four muscles or their ligaments that attach the muscle to bone can occur because of acute injury, chronic overuse, or gradual aging. This can cause significant pain and disability with range of motion or use of the shoulder joint.
The shoulder is a ball-socket joint that allows the arm to move in many directions. It is made up of the humeral head (the upper end of the bone of the upper arm) fitting into the glenoid fossa of the scapula (shoulder blade). The humeral head is kept in place by the joint capsule and labrum, thick bands of cartilage that form an elongated cone where the humeral head fits. The rotator cuff muscles are the dynamic stabilizers and movers of the shoulder joint and adjust the position of the humeral head and scapula during shoulder movement.When the rotator cuff is damaged, a variety of issues arise: * Pain and spasm limit the range of motion of the shoulder. * The muscles do not make the small adjustments within the joint to allow the humeral head to move smoothly. * Fluid accumulation within the joint due to inflammation limits movement. * Arthritis and calcium deposits that form over time limit range of motion.
Symptoms of a rotator cuff injury are due to the inflammation that accompanies the strain. This inflammation causes swelling, leading to the clinical picture of: pain and decreased range of motion; pain usually is worse at night and may interfere with sleep and it becomes worse with lifting the arm to the side (abduction) or turning it inward (internal rotation).
Not all shoulder pain arises from the shoulder. Sometimes pain from the heart can be referred to the shoulder, and pain from the gallbladder or diaphragm can also be felt in the shoulder region. A rotator cuff injury is worsened with shoulder movement. If the unexplained shoulder pain is not affected by movement, it is reasonable to seek immediate medical care.