The superficial palmar arch (superficial volar arch; arcus volaris superficialis) is formed by the ulnar artery, and is usually completed by a branch from the a. volaris indicis radialis, but sometimes by the superficial volar or by a branch from the a. princeps pollicis of the radial artery. The arch passes across the palm, describing a curve, with its convexity downward.
Relations.—The superficial volar arch is covered by the skin, the Palmaris brevis, and the palmar aponeurosis. It lies upon the transverse carpal ligament, the Flexor digiti quinti brevis and Opponens digiti quinti, the tendons of the Flexor digitorum sublimis, the Lumbricales, and the divisions of the median and ulnar nerves.
Three Common Palmar Digital Arteries (aa. digitales volares communes) arise from the convexity of the superficial palmar arch and proceed downward on the second, third, and fourth Lumbricales. Each receives the corresponding volar metacarpal artery and then divides into a pair of proper palmar digital arteries (aa. digitales volares propriæ; collateral digital arteries) which run along the contiguous sides of the index, middle, ring, and little fingers, behind the corresponding digital nerves; they anastomose freely in the subcutaneous tissue of the finger tips and by smaller branches near the interphalangeal joints. Each gives off a couple of dorsal branches which anastomose with the dorsal digital arteries, and supply the soft parts on the back of the second and third phalanges, including the matrix of the finger-nail. The proper volar digital artery for medial side of the little finger springs from the ulnar artery under cover of the Palmaris brevis.