Flexor muscle incursion into the carpal tunnel: a mechanism for increased carpal tunnel pressure?

PURPOSE: To explore the hypothesis that the extrinsic finger flexor muscles have the potential to move into the proximal end of the carpal tunnel with wrist extension. METHODS: The most distal muscle fibres from the deep and superficial finger flexors were measured relative to the pisiform bone in 18 cadaveric specimens. Muscle excursions during wrist extension were calculated using regression equations previously reported in the literature.