732 



THE VASCULAR SYSTEMS 



venosi digitales). From these arches take origin the four dorsal interosseous or 

 the interdigital veins (vv. metacarpeae dorsales). These veins form the dorsal 



venous plexus of the hand (rete venosum 

 dorsale mantis). This plexus lies in a 

 line with the lower ends of the shafts 

 of the metacarpal bones. It receives 

 the dorsal interosseous veins, the radial 

 digital vein of the index finger, and 

 numerous superficial veins from the 

 back of the hand. It gives origin to the 

 superficial radial vein and the posterior 

 ulnar vein. The superficial veins of 

 the palmar surface are of less size and 

 number than the dorsal veins. They 

 arise from each of the phalanges by a 

 plexus (vv. digitales volares propriae). 

 Vessels at the borders of the fingers 

 take most of the blood to the dorsal 

 veins. There are also veins in the 

 finger webs (vv. intercapitulares), which 

 convey the blood from the palm to 

 the dorsum. A superficial plexus, the 

 palmar plexus, lies upon the palmar 

 fascia, the fascia of the thenar emi- 

 nence, and the fascia of the hypothenar 

 eminence. 



The anterior ulnar vein (v. ulnaris 

 anterior) (Fig. 510) commences on the 

 anterior surface of the ulnar side of the 

 hand and wrist, and ascends along the 

 anterior surface of the ulnar side of the 

 forearm to the bend of the elbow, where 

 it joins with the posterior ulnar vein to 

 form the common ulnar. Occasionally 

 it opens separately into the median 

 basilic vein. It communicates with 

 tributaries of the median vein in front 

 and with the posterior ulnar behind. 



The posterior ulnar vein (v. ulnaris 

 posterior) (Fig. 509) commences on the 

 posterior surface of the ulnar side of 

 the wrist. It runs on the posterior sur- 

 face of the ulnar side of the forearm, 

 and just below the elbow unites with 

 the anterior ulnar vein to form the 

 common ulnar, or else joins the median 

 basilic and helps to form the basilic. It 

 communicates with the deep veins of 

 the palm by a vein which emerges from 

 beneath the Abductor minimi digiti 

 muscle. 



The common ulnar vein (v. ulnaris 

 communis) (Fig. 510) is a short trunk 



FIG. 510,-Thesu^erfidalvein^the flexor aspect of wh ^ h j g nQt constant \y hen it ex j sts 



Median cephalic. 



External 

 cutaneous nerve. 



( Internal 

 < cutaneous 

 ( nerve. 

 Median 

 basilic. 



^Common 

 ulnar. 



