Typing doesn't usually cause much problem with the ulnar nerve. The median nerve is more likely to be affected via carpal tunnel syndrome. The muscles that move your fingers are mostly located in your forearm, and connect to the fingers via tendons. The tendons run through a tube, called the tendon sheath. If you move your fingers while the wrist/hand is: bent down (flexed), bent backward (dorsiflexed), bent toward the side of the little finger (ulnar deviation), or bent toward the side of the thumb (radial deviation), the tendon will rub against the sheath and may create inflammation. Part of inflammation is swelling. There is a tough layer of connective tissue acros the wrist that holds the tendons down so that they don't jump straight from your forearm to the fingers when you bend you wrist and curl your fingers. The swelling cannot expand the space under that fascia (the carpal tunnel), and so puts pressure on the median nerve, affecting the palm side of the thumb, index, long, and half of the ring finger. The ulnar nerve supplies the palm side of the small finger and half of the ring finger.
Last edited by Sandy L
on Fri Jun 08, 2007 2:58 pm, edited 1 time in total.
I am a physician specializing in occupational and environmental medicine. I am not an authority on HMS or EDS, but find I have several patients with the condition and am trying to learn more.