THE VASCULAR SYSTEM 211 



A. e-pigastrica anterior and the A. hrachialis. Dorsally there arise 

 two smaller branches, the A. subscapularis^ and the A. circumflexa 

 scapulae. 



{b) The A. epigastrica anterior (a.e.a.) (A. cutanea magna, Bethge) 

 passes ventralwards round the body, deep to the M. pectoralis, but 

 lateral to the longitudinal muscles of the ventral body-wall. At the 

 lateral edge of the M. rectus abdominalis superficialis it turns abruptly 

 caudad along the ventral parietes, between the MM. rect. abd. 

 super, and rect. abd. profundus, and deep to the M. obliquus externus. 

 It gives off branches segmentally at each muscular inscription, and 

 unites finally with the A. epigastrica posterior — a branch of the 

 iliac artery — thus forming a complete arterial loop along the ventro- 

 lateral aspect of the trunk. Within the arm-pit the A. epigas. antr. 

 gives the following two branches: 



(i) A. supracoracoidea (a. sup. cor.) passing, with the nerve of the 

 same name, over the dorsal surface of the coracoid, through the 

 coracoid foramen, to supply the muscles arising from that bone. 

 This branch is always small and is sometimes absent. In the latter 

 case the muscles are supplied by a branch from the A. pectoralis 

 which passes forwards over the posterior margin of the coracoid on 

 its ventral aspect. The supracoracoid artery may apparently some- 

 times arise from the A. subclavia direct. 



(ii) A. pectoralis (a.pect.). Leaves the anterior epigastric artery just 

 before it turns caudad, and supplies the M. pectoralis and the skin 

 covering it. One of its branches — which sometimes arises separately 

 from the epigastric — turns anteriorly and enters the muscles cover- 

 ing the ventral surface of the coracoid. 



(<:) A. circumflexa scapulae (a.circ.sc.) arises dorsally from the sub- 

 clavian artery and passes round the lateral face of the scapula in 

 company with the V. circumflexa scapulae. It gives off the following 

 six branches: 



(i) A. profunda brachii (Osawa) (a. pf.br.). This artery enters the 

 arm dorsally just posterior to the insertion of the M. dorsalis hume- 

 ralis, and passes along the dorsal side of the humerus in company 

 with the extensor nerves. It supplies the several heads of the M. 

 anconaeus and the skin overlying it, and terminates finally in the 

 skin within the bend of the elbow — R. cutaneus brachii posterior 

 (Osawa). 



(ii) A. subscapularis (Osawa) (a.s.sc.) passes round the mesial side 

 of the scapula to the muscle of the same name. 



(iii) and (iv) RR. musculares to the MM. dorsalis humeralis and 

 dorsalis scapulae. These vessels enter the muscles mesially. 



