Vascular basis of dorsal digital and metacarpal skin flaps. A, Extended dorsal phalangeal island skin flap on dorsal aspect of proximal and middle phalanges. B, Boomerang flap on dorsal aspect of proximal phalanx (subcutaneous vascular pedicle of flap indicated by dashed lines). C, Reverse dorsal metacarpal artery island flap based on vascular anastomoses between dorsal cutaneous branches of palmar digital artery and dorsal digital branches of dorsal metacarpal artery. Arrows show direction of blood flow. Palmar digital artery (a); dorsal perforating branch of palmar metacarpal arteries from deep palmar arch (b); dorsal digital artery (c); dorsal cutaneous branches of palmar digital artery (d).