THE BRACHIAL OB AXILLARY ARTERIES. 



653 



that its internal divisions form with the anterior radial artery, and for those 

 which occasionally unite its external ramifications to the ultimate branches of 

 the interosseous artery of the forearm or the ulnar artery 

 (I'ig- 377, 2). 



1. FiEST Terminal Branch of the Posterior Radial 

 Artery (Radio-palmar), or Common Trunk of the 

 Interosseous Metacarpal Arteries^ (Figs. 376, 5; 

 377, 3). 



This arterial branch separates at a very acute angle from 

 the collateral artery of the cannon. It descends inside and 

 behind the carpus, accompanied by the principal subcutaneous 

 vein of the limb, and with it is included underneath a super- 

 ficial fascia, which maintains them in a channel hollowed on 

 the external face of the carpal fibrous sheath. It thus arrives 

 within the head of the inner metacarpal bone, where it is 

 inflected to the outer side by crossing the superior extremity 

 of the suspensory ligament, and between it and th^ metacarpal 

 ligament the latter furnishes to the perforans tendon ; it 

 anastomoses by inosculation with a descending branch which 

 emanates from the superficial arch that, above the carpus, 

 unites the ulnar artery to the origin of the collateral artery of 

 the cannon (Fig. 376). The loop-like anastomosis thus formed 

 by the radio-palmar artery exactly corresponds to the deep 

 palmar arch of pentadactylous animals, particularly to that of 

 Man. We propose to name it also the infra-carpal arch, by 

 reason of the position it occupies with regard to the carpus ; 

 reserving the appellation of supra-carpal arch for the superficial 

 palmar arch, which is represented by the anastomosis established 

 between the collateral artery of the cannon and the ulnar artery. 

 Four principal branches emanate from this infra-carpal 

 arch : these are the metacarpal interosseous arteries, distin- 

 guished as posterior or palmar, and anterior or dorsal. 



a. The posterior interosseous arise, one on the right, the 

 other on the left, at the head of the lateral metacarpal bones, 

 each descending on its own side and in a flexuous manner, 

 along these rudimentary bones, in the angular groove formed 



7- 



ARTERIES OF THE FORE FOOT, SEEN FROM BEHIND, 



The muscles and tendons have been removed, only a small portion of the 

 perforans tendons being left ; the os pedis has been chiselled away on its 

 plantar face to expose the semilunar anastomosis. 



1, Posterior radial artery; 2, innominate carpal branch; 3, supra-carpal 

 arch; 4, ulnar artery; 5, radio-palmar artery, or common trunk of the 

 Interosseous metacarpal arteries; 6, infra-carpal arch; 7, 7, posterior 



interosseous metacarpal arteries; 7', 7', anterior interosseous metacarpal arteries; 8, 8, their 

 origin; 9, collateral artery of the cannon; 10, its communicating branch with the interosseous 

 arteries; 11, U, digital arteries; 12, semilunar anastomosis in the os pedis; 13, emergent 

 branches of this anastomosis; 14, plantar imgual artery, forming the anastomotic arch; 15, origin 

 of the preplantar ungual artery; 16, origin of the plantar-cushion artery; 17, origin of the 

 anterior branch of the coronary circle; 18, posterior branch of the same. 



' This vessel corresponds to the radio-palmar artery ofiMan, by which uame it is sometimes 

 Jesignated. Rigot has improperly named it the deep plantar artery. 



