654 THE VASCULAR SYSTEMS 



The superficial palmar arch (arcus volaris superficialis) (Fig. 462) is formed 

 by the ulnar artery in the hand, and is usually completed on the outer side by 

 a branch from the radialis indicis, but sometimes by the superficialis volae of the 

 princeps pollicis of the radial artery. The arch passes across the palm, describing 

 a curve, with its convexity downward. 



Relations. The superficial palmar arch is cpvered by the skin, the Palmaris brevis, and 

 the palmar fascia. It lies upon the annular ligament, the Flexor brevis and Opponens minimi 

 digiti, the tendons of the Flexor sublimis digitorum, the Lumbrical muscles, and the divisions 

 of the median and ulnar nerves. 



PLAN OF THE RELATIONS OF THE SUPERFICIAL PALMAR ARCH. 



In front. 

 Skin. 



Palmaris brevis. 

 Palmar fascia. 



Behind. 



Annular ligament. 

 Flexor brevis minimi digiti. 

 Opponens minimi digiti. 

 Tendons of Flexor sublimis digitorum. 

 Lumbrical muscles. 

 Branches of median and ulnar nerves. 



Branches. The branches of the Superficial palmar arch are: 



Four Digital Arteries. 



Four digital arteries (aa. digitales volares communes) (Fig. 462) are given off 

 from the convexity of this arch. The innermost accompanies the inner digital 

 branch of the ulnar nerve, and runs along the ulnar side of the little finger; it is 

 joined by a twig from the deep palmar arch or from the innermost palmar inter- 

 osseous artery. The three outer run downward in front of the three inner inter- 

 osseous spaces, superficial to the corresponding nerves and Lumbrical muscles. 

 A little above the interdigital clefts they are joined by the palmar interosseous 1 

 arteries, and by the inferior perforating branches of the dorsal interosseous arteries. 

 Each then divides into collateral digital arteries (aa. digitales volares propriae) \ 

 for the supply of the contiguous sides of the index, middle, ring, and little fingers. 

 These collateral branches lie behind the corresponding digital nerves; they 

 anastomose freely in the subcutaneous tissue of the finger tip and by smaller 

 branches near the interphalangeal joints. Each supplies 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. 



Surface Marking. The superficial palmar arch is represented by a curved line, starting 

 from the outer side of the pisiform bone and carried downward as far as the middle third of 

 the palm, and then curved outward on a level with the upper end of the cleft between the thumb 

 and index finger. The deep palmar arch is situated about half an inch nearer to the carpus. 



Applied Anatomy. Wounds of the palmar arches are of special interest, and are always 

 difficult to deal with. When the superficial arch is wounded it is generally possible, by enlarging 

 the w T ound if necessary, to secure the vessel and tie it' or in cases where it is found impossible to 



