This article is from the Ergonomics and Typing Injury FAQ, by Dan Wallach firstname.lastname@example.org with numerous contributions by others.
First, and foremost of importance: if you experience pain at all, then you
absolutely need to go see a doctor. As soon as you possibly can. The difference
of a day or two can mean the difference between a short recovery and a long,
drawn-out ordeal. GO SEE A DOCTOR. Now, your garden-variety doctor may not
necessarily be familiar with this sort of injury. Generally, any hospital with
an occupational therapy clinic will offer specialists in these kinds of
problems. DON'T WAIT, THOUGH. GO SEE A DOCTOR.
The remainder of this information is paraphrased, without permission, from a
wonderful report by New Zealand's Department of Labour (Occupational Safety and
Health Service): "Occupational Overuse Syndrome. Treatment and Rehabilitation:
A Practitioner's Guide".
First, a glossary (or, fancy names for how you shouldn't have your hands):
(note: you're likely to hear these terms from doctors and keyboard vendors :)
Repetitive Strain Injury - a general term for many kinds of injuries
Occupational Overuse Syndrome - synonym for RSI
Cumulative Trauma Disorder - another synonym for RSI
Work-Related Upper Limb Disorders - yet another synonym for RSI
Carpal Tunnel Syndrome (see below)
Marked bending at a joint.
Turning the palm down.
Bending the wrist up.
Turning the palm up.
Bending the wrist down.
The grip used for a pencil.
Bending the wrist towards the little finger.
The grip used for a hammer.
Bending the wrist toward the thumb.
Moving away from the body.
Opening the fingers out wide.
Now then, problems come in two main types: Local conditions and diffuse
conditions. Local problems are what you'd expect: specific muscles, tendons,
tendon sheaths, nerves, etc. being inflamed or otherwise hurt. Diffuse
conditions, often mistaken for local problems, can involve muscle discomfort,
pain, burning and/or tingling; with identifiable areas of tenderness in
muscles, although they're not necessarily "the problem."