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Backpacker Magazine – BACKPACKER.com Online Exclusive
A personal perspective on healing back, joint and other body pains.
So now a look at joints.
Almost all voluntary movement in the human body involves tendons moving across joints. Look at the inside of your wrist and make a fist. The stringy cords that you see shifting under the skin are tendons. These particular ones connect the muscles of your forearm to your wrist and fingers, allowing them to work.
Tendons are attached to muscles on one end and to bones at an insertion point on the other. On the way from muscle to bone, the tendon passes through a tendon sheath, which is attached to the underlying bone. When the muscle flexes it contracts, shortening and drawing the tendon toward the muscle. The sheath stabilizes the tendon and acts as a pulley. Without the tendon sheath the tendon would straighten as a rope does when it is tied to a weight and pulled. The tendon sheath keeps the tendon near the bone, increasing the efficiency of the system and preventing us from looking funny when we flex a muscle.
The sheath secretes synovial fluid, the same viscous, slimy fluid that keeps joints lubricated and your lungs stuck effortlessly to your chest wall while allowing the lungs to move freely as the chest wall moves.
When you've ski-poled your way on snowshoes up many a slope--gripping the pole, shoving with elbow and shoulder--a tendon may be overworked. The sheath tries to keep things running smoothly by secreting more fluid, but the sheath can't expand to hold the increase in fluid, so the tendon is compressed. The tendon and the sheath swell and inflammation begins. Now the tendon calls for more lubrication and the sheath responds with more fluid and the problem increases each time that particular tendon is used. What develops is tendinitis. Or, as some medical books spell it, tendonitis. Even though no tendon is immune to trouble, some parts of your body are more susceptible than others--shoulders, wrists, and elbows, for example.