This could be either: suprafascial, subfascial, or absent.The suprafascial artery (16 cases) ran along the thumb metacarpal, lying on the ®rst dorsal interosseous muscle just below its aponeurosis (Fig 5). Its distance from the longitudinal central axis of the thumb metacarpal was 15mm at its base and 5mm at its distal third. It gives off osteoperiosteal branches in four main sites. The base of the thumb metacarpal received a twig from the radial branch (13 cases) or from the radial artery. There were two branches for the diaphysis (20mm and 30mm from the metacarpophalangeal joint) and one branch for the head of the thumb metacarpal.