540 



THE BLOOD-VASCULAR SYSTEM. 



Radial recurrent. 



The anterior carpal is a small vessel which arises from the radial artery near the 

 lower border of the Pronator quadratus, and, running inward in front of the radius, 



anastomoses with the anterior carpal 

 branch of the ulnar artery. In this 

 way an arterial anastomosis, anterior 

 carpal arch, is formed in front of the 

 wrist ; it is joined by branches from 

 the anterior interosseous above, and 

 by recurrent branches from the deep 

 palmar arch below, and gives off 

 branches Avhich descend to supply 

 the articulations of the wrist and 

 carpus. 



The superficialis volae arises from 

 the radial artery, just where this 

 vessel is about to wind round the 

 wrist. Running forward, it passes 

 between, occasionally over, the mus- 

 cles of the thumb, which it supplies, 

 and sometimes anastomoses with the 

 palmar portion of the ulnar artery, 

 completing the superficial palmar 

 arch. This vessel varies consider- 

 ably in size : usually it is very small, 

 and terminates in the muscles of the 

 thumb ; sometimes it is as large as 

 the continuation of the radial. 



The posterior carpal is a small 

 vessel which arises from the radial 

 artery beneath the extensor tendons 

 of the thumb ; crossing the carpus 

 transversely to the inner border of 

 the hand, it anastomoses with the 

 posterior carpal branch of the ulnar, 

 forming the posterior carpal arch, 

 which is joined by the termination 

 of the anterior interosseous artery. 

 From this arch are given off descend- 

 ing branches, the dorsal interosseous 

 arteries for the third and fourth in- 

 terosseous spaces, which run forward 

 on the Third and Fourth dorsal in- 

 terossei muscles, and divide into 

 dorsal digital branches which supply 

 the adjacent sides of the middle, 

 ring, and little fingers respectively, 

 communicating with the digital 

 arteries of the superficial palmar 

 arch. At their origin they anasto- 

 mose with the perforating branches 

 from the deep palmar arch. 



The metacarpal (first dorsal inter- 

 osseous branch) arises beneath the ex- 

 tensor tendons of the thumb, some- 

 times with the posterior carpal 

 artery ; running forward on the Second dorsal interosseous muscle, it communicates, 

 behind, with the corresponding perforating branch of the deep palmar arch ; and 



Deep branch 

 of ulnar. 



Superficialis volae. 



FIG. 304. The radial and ulnar arteries. 



