920 



THE VASCULAE SYSTEM. 



(4) A volar carpal branch passes ulnarwards, between the flexor tendons and their 

 synovial sheaths, and the radial attachments of the volar carpal ligaments. It anasto- 

 moses with the volar carpal branch of the ulnar artery to form the volar carpal arch 



and it receives communications from 

 the volar interosseous artery and 

 from the deep volar arch. 



Relations of the Second 

 Part. As it curves round the radial 

 side and the dorsum of the wrist, the 

 radial artery lies upon the radial 

 collateral ligament of the intercarpal 

 joint and upon the back of the os 

 multangulum majus. It is crossed 

 by the abductor pollicis longus, the 

 extensor pollicis brevis, and the ex- 

 tensor pollicis longus; more super- 

 ficially it is covered by skin, and by 

 fascia, which contains the cephalic vein 

 and some filaments of the superficial 

 branch of the radial nerve. 



Branches of the Second 

 Part (1) Dorsales Pollicis. Two 

 small arteries which run along the 

 borders of the dorsal aspect of the 

 thumb ; they supply the skin, ten- 

 dons, and joints, and anastomose 

 with the volar digital arteries. 



(2) Dorsalis Indicis Radialis. 

 A slender artery which runs dis- 

 tally, on the ulnar head of the first 

 dorsal interosseous muscle and along 

 the dorsal aspect of the radial border 

 of the index-finger. 



(3) and (4) The first dorsal 

 paimaris metacarpal and the dorsal radial 



longus 

 Median artery 



Biceps 

 Brachial artery 



Median nerve 



Radial nerve (O.T. 



musculo-spiral 



Radial recurrent 



artery' 



Brachialis 



Brachio- 

 radialis 



Supinator_ 

 Radial recurrent 

 artery" 



Supinator-- 



Flexor digitorum 

 sublimis" 



Radial artery 



Radialis indicis 

 artery 



Ulnar 

 artery 



Pronator 

 teres 



Flexor pollicis Ion 



Ulnar artery 



Flexor carpi 

 radialis 



Ulnar nerve 



Superficial volaris 

 artery 



carpal arise by a common trunk 

 which crosses deep to the extensor 

 pollicis longus. 



Deep branch 

 of ulnar artery 



Superficial 

 volar (palmar) 

 arch 



Digital 

 arteries 



(a) The metacarpal branch passes 

 distally, on the dorsal aspect of the 

 second dorsal interosseous muscle, and 

 divides, opposite the heads of the meta- 

 carpal bones, into two dorsal digital 

 branches which supply the adjacent 

 sides of the index and middle fingers. 

 (6) The dorsal carpal branch runs ulnar- 

 wards, on the dorsal carpal ligaments, 

 deep to the extensor tendons, to anas- 

 tomose with the dorsal carpal branch of 

 the ulnar artery, and to complete the 

 dorsal carpal arch which receives the 

 terminations of the volar and dorsal 

 interosseous arteries. The dorsal carpal 

 arch gives off the second and third 

 dorsal metacarpal arteries, which run 

 distally, on the dorsal aspects of the 

 third and fourth dorsal interosseous 

 muscles, as far as the heads of the meta- 

 carpal bones, where each divides into 

 two dorsal digital branches for the ad- 

 jacent sides of the third and fourth and 

 the fourth and fifth digits, respectively. 

 Each dorsal metacarpal artery is connected with the deep volar (palmar) arch by a proximal 

 perforating branch which passes through the proximal part of the corresponding interosse 

 space, and with a digital branch from the superficial volar (palmar) arch by a distal perforating 

 branch which passes through the distal part of the space. 



FIG. 768. SUPERFICIAL DISSECTION OF THE VOLAR ASPECT 

 OF THE FOREARM AND HAND, showing" the radial and 

 ulnar arteries and the superficial volar arch with its 

 branches. 



