ARTERIES OF THE HAND. 733 



The interosseous artery arises just below the last, and 

 divides after a short course into two branches, an anterior 

 and a, posterior. 



The anterior interosseous artery descends in front of the 

 interosseous ligament behind the deep flexors to the prona- 

 tor quadratus, where it penetrates this ligament to the 

 back of the wrist, and anastomoses with the radial and 

 posterior interosseous. 



The posterior interosseous artery is the smaller branch, 

 and sometimes arises as a separate trunk ; it soon passes 

 through the interosseous ligament to the back of the arm, 

 and then descends to supply the extensor muscles. At its 

 upper end it gives off a recurrent branch to the posterior 

 part of the elbow, which anastomoses with the recurrens 

 radialis and ulnaris. 



Muscular branches, numerous and irregular, are given off 

 in its course. 



The dorsalis carpi ulnaris comes off at the lower end of 

 the ulna, and winds beneath the flexor ulnaris tendon to 

 the back of the wrist, where it anastomoses with the radial 

 and interosseal, to supply the carpus, metacarpus, and 

 phalanges. 



Varieties. The ulnar artery may arise from the axillary, 

 the interosseal from the radial, brachial, or axillary. In- 

 deed it is difficult to say what will be the distribution of 

 the arteries of the forearm until it is examined. 



ARTERIES OF THE HAND, (Fig. 236.) 



The arcus sublimis or superjicicdis is the continued trunk 

 of the ulnar artery, and extends from the lower border of 

 the annular ligament across the palm of the hand to the 

 thumb, to anastomose with the radial ; after supplying 

 the muscles of the palm, it sends deeply a larger branch, 

 called cubitalis manus profunda, to unite with the arcus 

 profundus. 



It next sends off the digital arteries. These are four in 

 number ; the first goes on the ulnar side of the little finger ; 

 the others proceed to the heads of the metacarpal bones, 



