Carpal tunnel syndrome manifests as numbness and/or pain in the hand due to compression of one of the major nerves of the hand. The arrangement of the structures in the hand is responsible in part for carpal tunnel syndrome. These structures include the Median Nerve and the tendons which "flex" or bend the fingers at the knuckles. The nerve and tendons pass through the carpal tunnel, which (as the name states) is a tunnel which passes over the "carpal" bones of the hand. The roof of the tunnel is made of a strip of tissue which is connected on either side to the carpal bones.
In this graphic, the carpal tunnel is shown with the tendons (brown) and the median nerve (red) passing through the carpal tunnel (green). When the muscles of the forearm pull the tendons, the fingers flex (see arrows).
This arrangement is similar to placing a telephone cable in a conduit which already holds mechanical cables. Any damage that the mechanical cables cause to the conduit may affect the integrity of the telephone cable. Similarly, when a disease process or "repetetive movement" of the tendons damages the supporting tissues in the carpal tunnel and causes swelling or scar formation, the median nerve is compressed and its function (which includes carrying sensory perception) is affected, and numbness and pain ensue.
In the graphic on the right, the carpal tunnel is seen in cross section as if you, the viewer, were going to pass through the tunnel. The roof is green and the carpal bones form the floor and walls. The pink material represents the supporting tissue which, when damaged, becomes swollen or scarred and compresses the nerve (shown in red).
Note: The material provided in this web page is educational in nature and not medical advice. It is meant neither for self-diagnosis nor as a treatment recommendation. If you are concerned about any condition you think you may have, CONSULT YOUR DOCTOR.