The dorsal branch of the ulnar artery branched from the ulnar artery approximately 3 cm from the styloid process of the ulna and passed dorsally under the flexor carpi ulnaris muscle. After giving off muscular and osseous branches to the flexor carpi ulnaris muscle and the pisiform bone, two cutaneous ascending and descending branches followed the fascial layer of the flexor carpi ulnaris muscle longitudinally (Fig. 15.1).

After it had given off a branch that contributed to the dorsal carpal arch, a descending branch of the dorsal ulnar artery coursed to the radial and ulnar sides of the fifth metacarpal. The ulnar branch had numerous microvascular connections to the underlying fascia of the hypothenar muscle. The mean arterial diameter of this branch (at a site branching to the dorsal carpal arch) was 0.5 mm. This descending branch gave off two to four skin perforators between the ulnar styloid and the fifth metacarpal and supplied the ulnar aspect of the dorsal wrist, where it was located over the sixth compartment of the extensor retinaculum. Communications from the dorsal branch of the ulnar artery to the palmar arterial system at the fifth metacarpal head were present in all specimens.

The venous drainage of the radial and ulnar aspects of the dorsum of the wrist was partly from the concomitant veins of the neurocutaneous perforating arteries from the dorsal branches of the radial and ulnar arteries and partly from the subcutaneous cephalic and basilic venous system.

A 25-year-old man sustained a crush amputation to his middle and ring finger by a machine. Replantation was impossible, and the palmar site of little finger was necrotized. Because he wished to keep the little finger as long as possible, the flap procedure was planned for coverage of its exposed bone and tendon (Fig. 15.2).