[Surgical anatomy of the carpal tunnel].

The carpal tunnel is the pathway between the flexor compartment of the distal forearm and the midpalmar space of the hand. It contains all the long finger and thumb flexor tendons including the median nerve. In cases of a discrepancy between the volume of the carpal tunnel in relation to its contents, high pressures in this region can result. There is a risk that the median nerve will be sustained by compression. The carpal tunnel is covered by the flexor retinaculum. Length and width of the retinaculum correspond to the extension of the tunnel. Radial und ulnar osseous walls can narrow the tunnel diameter as well as an prominent capitate bone at the floor. The median nerve normally courses the tunnel radially near the middle of the flexor retinaculum far reaching straight to the midpalmar region. Several deviations of its tunnel course, atypical divisions, accessory branches and variations of the ramification of the thenar branch of the median nerve are described.