Computer Pain: Back and Shoulders

The shoulder is pretty unique. As I mentioned previously, it’s made up of several joints, but the one we commonly think of as “the shoulder” is the glenohumeral joint. This joint is a ball-and-socket joint (see image #1 here), which means that it’s free to move in almost any direction (as opposed to, say, the hinge joints that make up your knuckles).

The human body has only two examples of the ball-and-socket joint: the shoulders and the hips. Because the hips are used primarily for structure and support (ie, holding up the upper half of your body), its possible motions are tempered by strong tendons and ligaments. Shoulders, on the other hand, must allow for a variety of motions – throwing a football, holding an infant, lifting a boombox over your head. In order to accomplish this, the joint must be stable but generally unrestricted.

As a side note, this mobility in the shoulder is the reason why it can dislocate so easily.

There are four muscles that help to stabilize the glenohumeral joint, and they make up the group known as the rotator cuff. I already spoke about one of them, the subscapularis, so now it’s time to meet the remaining three.

Not shown: teres major, trapezius

Of these three muscles, teres minor and infraspinatus are the most important. They work in tandem to stabilize the joint and move the shoulder in many directions. Their most important action, however, is external rotation – rotating the shoulder out, away from the center line. Not surprisingly, this is the opposing action to that of the subscapularis and the pectoralis major, which both help to rotate your shoulders inward. As the subscap and pecs shorten, your shoulders hunch forward. To compensate for this, the teres minor and infraspinatus must lengthen (see here).

You may think, “Well, lengthening is just stretching, right? It can’t be all that bad.” But imagine holding a stretch for hours at a time. Eventually, the muscles get irritated, maybe even injured. The muscles tighten up. Trigger points arise.

Properly sitting at a desk isn’t about stretching or exercising. It’s about having good posture; maintaining a stationary position while keeping your muscles loose and relaxed.

The last rotator cuff muscle, the supraspinatus, is not as troublesome as its brothers. Besides stabilizing the shoulder, this muscle assists the deltoid in lifting up the arm. I don’t see nearly as many problems in this muscle as I do in the others. But with three out of the four rotator cuff muscles causing problems, I usually have enough to work on.


Wrists and Elbows
Shoulders and Chest
Back and Shoulders

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