The wrist contains a small tunnel made up of the carpal bones. The median nerve and nine (9) tendons that control the fingers and the thumb travel through this tunnel. With all the traffic going through such a small space, when the nerve or tendons swell with irritation or when the tunnel narrows it compresses the various tissues. This compression can result in numbness, tingling, pain and weakness in grip strength and motion.
For more information visit the American Academy of Orthopaedic Surgeons: https://orthoinfo.aaos.org/en/diseases–conditions/carpal-tunnel-syndrome/