[Dorso-ulnar thumb flap].

The arterial supply of the dorsal surface of 25 thumbs was studied with the help of a light microscope. An arterial vessel, localized on the dorso-ulnar side and connecting the head of the first metacarpal bone with the dorsal arcade of the nail matrix was constantly found in all dissections. The author reports the results of the anatomical study and the clinical applications of a skin flap which can be raised on the dorso-ulnar surface of the MP joint with a distal pedicled. Clinical experience is based on 9 flaps for coverage of distal skin defects (dorsal or volor) of the thumb.