Type I (normal type, 18/30, 60%): S

Type I (normal type, 18/30, 60%): Similar to the 2nd–4th dorsal metacarpal arteries, this type of first dorsal metacarpal artery also had three terminal branches; however, its branches presided the others. The radial branch passed along the dorsum of the first metacarpal bone and continued as the ulnar dorsal digital artery of the thumb. The ulnar branch passed along the radial of the second metacarpal bone and continued as the radial dorsal digital artery of the index finger. The intermediate branch passed along the first dorsal interosseous muscle to distribute at the first web space.