THE AKTEEIES, 233 



round the humerus with the radial nerve between the muscles of the 

 outer side of the forearm, to which it gives branches : in the palm 

 of the hand it passes between the M. extensor carpi îdnaris and the 

 M. flexor antihrachii to the dorsal surface of the hand, where it 

 anastomoses with the ulnar artery. In its course it supplies :— 



(i) Muscvilar branches to the surrounding' muscles. 



(2) The Bam. cut. radialis inferior, which arises from the radial 

 artery towards the distal end of the forearm, and passes underneath 

 the M. flexor carpi ulnaris to the skin. 



B. The ulnar artery (Arteria nlnaris), (Figs. 150 U, 151 B) ac- 

 companies the ulnar nerve towards the hand, passes between the 

 M. flexor digitorum communis and the M. anconeus to the palm of the 

 hand, and then winds round the outer side to the dorsal surface 

 of the carpus to form its terminal branches. The branches are : — 



(i) The Rayn. cntan, med. inferior (Fig. 151 ci); it arises near 

 the wrist- joint and supplies (a) twigs to the skin of the inner sur- 

 face ; (/3) a branch downwards, which courses along the inner side 

 of the second finger to its tip; and (y) a branch which passes 

 upwards to anastomose with the B. cutaneus m.edialis superior. 



(2) In the palm of the hand a branch (Fig. 151 d) is given off, 

 which divides to form Arteriae digitales volares : one for the second 

 finger, two for the third finger, two for the fourth finger, and one 

 for the fifth finger. 



(3) Given off on the dorsum of the hand (Fig. 152) it supplies 

 branches corresponding exactly with those of the palmar surface. 



5. The dorsal aorta (Aorta communis s. ahdominalis (Fig. 153^). 

 The two systemic arches unite at about the level of the sixth vertebra 

 to form the dorsal aorta : as already mentioned the union is very 

 incomplete, the dorsal aorta being practically a continuation of the 

 right systemic arch, and only communicating with the left by 

 means of a small opening. The branches are as follows : — 



a. The coeliaco-mesenterie artery [Arteria intestinalis communis), 

 (Fig. 153), the true continuation of the left systemic arch, at once 

 divides to form the gastric and mesenteric arteries. 



(i) The gastric artery (Arteria gasirica s. coeliaca) (c) immediately 

 divides into two branches : — 



a. The Bamxis dexter s. anterior ; this artery gives off the Arteria 

 Iiepatica to the liver and gall-bladder and passes to the right (an- 

 terior) surface of the stomach, running along the attachment of the 



