MEDIAN NERVE DISPLACEMENT THROUGH THE CARPAL CANAL

We determined the direct relationships between wrist position and disp lacement of the median nerve during active contraction of the flexor t endons at the wrist with an intact, transected transverse carpal ligam ent (TCL). Nine fresh cadavers were mounted in an apparatus to allow v ariable wrist position. Excursions of the tendons and displacement of the median nerve were measured by tracking markers with a video camera . Each limb was tested at 0 degrees, 30 degrees, and 60 degrees of wri st extension before and after release of the TCL. Excursion of the fle xor tendons required for full finger flexion ranged from 2.3 to 3.1 cm (mean, 3 cm). Median nerve displacement ranged from 0.9 to 1.4 cm (me an, 1 cm). The relationship between median nerve and flexor tendon exc ursion was consistently linear. Finger motion alone allows Tot median nerve displacement after surgery in the carpal tunnel.