Venous anatomy of the thumb.

The venous anatomy of 20 thumbs (10 pairs) was detailed by latex injection. The thumbs were studied on the dorsal, palmar, radial, and ulnar surfaces. Characteristic patterns were found; these included a dominant longitudinal network, palmar veins within the pulp, oblique veins at the interphalangeal joint on the radial side, and a web space vein. A layered vascular pattern with a superficial fine network overlying a deeper system was noted. Cross sections were taken at the metacarpophalangeal joint and at the proximal and distal phalanges. The distribution of the vessels in cross section reveals consistent dorsal veins at all levels, as well as palmar veins distal to the interphalangeal joint in all thumbs. Palmar veins were present over the length of the proximal phalanx in more than 65% of the thumbs.