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THE ARTERIAL ARCHES OF THE WRIST AND HAND. 791 
carpus, where it unites with the posterior carpal branch of the radial to form the posterior 
earpal arch. 
(7) Profunda (ramus volaris profundus). — This branch descends between the 
abductor and flexor brevis minimi digiti, and, turning outwards beneath the flexor brevis, 
the opponens minimi digiti, and the flexor tendons and their sheaths, joins the 
termination of the radial artery to complete the deep palmar arch. 
THE ARTERIAL ARCHES OF THE WRIST AND HAND. 
Anterior more Arch (Fig. 564).—The anterior carpal arch lies on the 
front of the carpus behind the flexor tendons and their synovial sheaths. It is 
formed by the union of the anterior carpal branches of the radial and ulnar 
arteries, and it receives the c ommnuuicating branch from the anterior interosseous 
artery above and recurrent branches from the deep palmar arch below. The 
branches of distribution which pass from it are distributed to the ligaments and 
synovial membranes of the wrist and of the intercarpal and carpo-metacarpal 
joints. 
Posterior or Dorsal Carpal Arch (Fig. 565).—This arch hes on the posterior 
carpal ligaments under cover of the extensor tendons and their sheaths. It is 
formed by the union of the dorsal carpal branches of the radial and ulnar arteries, 
and receives the terminations of the anterior and posterior interosseous arteries. 
Branches. —(«) Articular to the adjacent articulations. (+) Dorsal interosseous, 
two slender branches which run downwards on the third and fourth dorsal interosseous 
muscles to the clefts of the fingers, where each divides into collateral branches. They 
communicate near their origins with the deep palmar arch by the superior perforating 
arteries, and near their terminations with the palmar digital vessels through the inferior 
perforating arteries. Their collateral terminal branches run downwards on the dorso- 
lateral aspects of the fingers which bound the third and fourth interosseous spaces, and 
they anastomose with the collateral digital branches of the palmar digital arteries. 
Superficial Palmar Arch (arcus volaris superficialis, Fig. 563).—This arterial 
arch includes the terminal portion of the ulnar artery, and is usually completed 
externally by the superficialis vole, or sometimes by the radialis indicis, or the 
princeps pollicis. It extends from the ball of the little finger to the inner border 
of the superticial head of the flexor brevis pollicis, and reaches as low down as a 
line drawn across the palm at the level of the lower border of the fully abducted 
thumb. It is covered by the integuments and the central portion of the palmar 
fascia, and, on the ulnar side of the palm, by the palmaris brevis, and it is 
accompanied by venze comites. It is in contact behind with the flexor brevis and 
Opponens minimi digiti, and with the digital branches of the ulnar and median 
nerves, as well as with the flexor tendons and the lumbrical muscles. 
Branches.—Four digital arteries (aa. digitales volares communes) arise from the 
convexity of the arch. The innermost descends along the ulnar border of the little finger, 
accompanied by the internal digital branch of the ulnar nerve ; the outer three pass down- 
wards superficial to the digital nerves, along the middle of the three inner interosseous 
spaces towards the interdigital clefts, just above which each digital artery divides into 
two collateral digital arteries (aa. digitales volares proprii), which supply the 
contiguous sides of the fingers bounding the cleft. As the collateral digital branches 
descend along the sides of the fingers they lie superficial to the corresponding digital 
nerves, and supply branches to the joints, to the flexor tendons with their sheaths, and to 
the skin and subcutaneous tissues on the palmar surface ; they also send backwards dorsal 
branches which anastomose with the dorsal digital arteries and supply the tissues on the 
dorsal aspects of the second and terminal phalanges. Some of the backwardly-directed 
branches form a plexus in the matrix of the nail. In the pulp of the finger-tips anasto- 
mosing twigs join to form arches from which numerous branches are given off to the skin 
and subcutaneous fat. 
Kach of the outer three digital arteries is joined immediately above its division by a 
palmar interosseous branch from the deep palmar arch and an inferior communicating 
artery from the dorsal interosseous. The innermost digital artery is joined by a branch 
which comes either from the inner palmar interosseous artery or from the deep palmar 
arch. 
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