600 



THE ARTERIES. 



recurrent. 



Posterior 

 interosseous. 



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 arises from the radial artery beneath the extensor tendons 



of the thumb ; crossing the carpus 

 transversely to its inner border, it 

 anastomoses -with the posterior car- 

 _Anastomotica pal branch of the ulnar, forming the 

 magna. posterior carpal arch, Avhich is joined 



by the termination of the posterior 

 interosseous artery. From this arch 

 are given off descending branches, 

 the dorsal interosseous arteries for 

 the third and fourth interosseous 

 spaces, which run forward on the 

 -Anterior ulnar musc i es an( j Divide into dorsal digi- 



recurrent. 9 



Posterior ulnar tal branches which supply the adja- 

 cent sides of the middle, ring, and 

 little fingers respectively, communi- 

 cating with the digital arteries of 

 the superficial palmar arch. At 

 their origin they anastomose with 

 the superior perforating branches 

 from the deep palmar arch, and at 

 the clefts of the fingers send off 

 inferior perforating branches to the 

 corresponding palmar digital ar- 

 teries. 



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 interosseus muscle, it 

 communicates, behind, with the 

 corresponding superior perforating 

 branch of the deep palmar arch : 

 and in front it divides into two 

 dorsal digital branches, which supply 

 the adjoining sides of the index and 

 middle fingers, inosculating with the 

 digital branch of the superficial 

 palmar arch. It also has a similar 

 but more constant inferior perfor- 

 ating branch, 



The dorsales pollicis are two 

 vessels which run along the sides of 

 the .dorsal aspect of the thumb. 

 They arise separately, or by a com- 

 mon trunk, near the base of the first 

 metacarpal bone. 



The dorsalis indicis runs along the radial side of the back of the index finger, 

 sending a few branches to the Abductor indicis. 



The princeps pollicis arises from the radial just as it turns inward to the deep 

 part of the hand; it descends anterior to the Abductor indicis and between the 

 Adductor pollicis muscles, along the ulnar side of the metacarpal bone of the thumb, 

 to the base of the first phalanx, where it divides into two branches, which run along 

 the sides of the palmar aspect of the thumb and form an arch on the under surface 



Muscular. 



Anterior carpal. 

 Superficialis wise. 



Anterior carpal. 



Deep branch of 

 ulnar. 



FIG. 365. Ulnar and radial arteries. Deep view. 



