As a Neuromuscular Therapist practicing in the Boston area for nineteen years, how do I think about the causes of pain in the shoulder and arm when patients lift their arms or reach for something?
With everyone on computers now, it is a common problem to have a work station that is too high and necessitates lifting of the arms to type or move the mouse. Anyone who works at a job that requires repetitive lifting or reaching is subject to these injuries. It is also a common complaint among athletes who lift their arms to throw or hit a ball. The problem is mainly chronic tension and lack of blood flow (ischemia) in one specific muscle of the rotator cuff group that lifts the arm (supraspinatus), but usually the entire group gets involved as well as accessory muscles in the top of the shoulder.
If the muscle is left untreated or improperly treated, two things can happen. First, the condition can become a tendonitis or bursitis from the constant rubbing of the tendon against the bone above it or across the bursa meant to pad and protect it from friction. Second, it may require surgery to 1) repair a frayed tendon, 2) remove bone spurs that form during chronic inflammation or 3) remove part of the bone (acromion process) at the outside tip of the shoulder (acromioplasty) to create more space for the arm to move in the shoulder joint.
When the space becomes too small for the tendon to move back and forth when the arm is raised and lowered, it is called an impingement. It’s painful!
As I’ve said before, when you’re a hammer, everything looks like a nail. I’m a Neuromuscular Therapist, so I’m always looking at Trigger Points as causes of pain. This little supraspinatus muscle nestles in a hollow in the shoulder bone underneath the upper and middle trapezius muscles at the very top of your shoulder. It’s tendon goes out under the acromion process and attaches to the top of the upper arm bone (humerus). When it contracts or shortens, it pulls on the humerus like a puppet string to raise the arm up from your side to shoulder height. When it becomes chronically ischemic, it can develop a Trigger Point, or nodule of hyperactivity that refers pain outward from that point. Guess where the supraspinatus refers? To the top of the upper arm (deltoid)! So there you have another good reason for pain in the arm.
In general, I look for four reasons for pain: 1) local muscle dysfunction or injury, 2) Trigger Points, 3) joint dysfunction, and 4) nerve involvement either as compression at the spine, or as entrapment in contracted soft tissue or by the taut band of a Trigger Point. So of those four reasons, I’ve covered joint pain and Trigger Point pain. Local muscles like this supraspinatus or the trapezius above it or the deltoid at the top of the arm could be painful from an injury like a rotator cuff tear or just from chronic tension with accumulated waste products. Considering nerve involvement here, it could be from compression of a spinal nerve in the neck, but there are no major nerves here locally to be entrapped by the muscles.
The next post is about treatment.