[Topology of the carpal tunnel in dynamic stress of the wrist joint].

Alterations of the spatial geometry of the carpal tunnel and its contents during dynamic stress situations of the wrist are of importance in clarifying morphological causes of a carpal tunnel syndrome. In order to demonstrate the changes occurring in the form of the carpal tunnel and the location of its contents during wrist movement, casts of the carpal tunnel were produced from the hands of cadavers in flexed and extended positions. The casts were then morphometrically analyzed and the movements of the median nerve and the flexor tendons were examined radiologically. The investigation showed that a delicate equilibrium exists between the capacity of the carpal tunnel--whose hourglass shape typically changes to suit dynamic stress situations--and the volume of its contents. Spatial processes extending from the carpal tunnel wall or emanating from the structures contained within the carpal tunnel may exceed the system's ability to compensate for extreme positioning of the wrist and thus induce compression symptoms of the median nerve.