304 THE CIRCULATORY SYSTEM. 



descending portions of the large intestine. It divides and sends 

 branches in both directions which anastomose with the cohca 

 dextra and with branches from the inferior mesenteric arteries. 



3. A. colica dextra. — A small branch which passes to the 

 ascending and transverse colon, anastomosing with the colica 

 media and ileocolica. It is sometimes absent. 



4. A. ileocolica. — This passes to the caecum and supplies 

 that structure, sending branches to the ileocolic valve and the 

 caudal end of the ileum, and anastomosing with the colica 

 dextra and the intestinal branches of the superior mesenteric. 



5. The superior mesenteric now divides into about sixteen 

 terminal branches which pass to the small intestine. In many- 

 cases these branches unite near the intestine, forming arches, 

 and from these arches numerous short branches pass to the 

 intestine. 



3. A. adrenolumbalis (or lumboabdominalis) (Fig. 126, e). 

 — This rises from the aorta, one on each side, about two 

 centimeters caudad of the superior mesenteric. Each passes 

 laterad onto the dorsal body wall, supplying the muscles of this 

 region. A large branch passes caudad along the surface of the 

 muscles dorsad of the kidney and anastomoses with the ilio- 

 lumbar artery. From the adrenolumbalis rises usually: 



A. phrenica (/). — The phrenic artery rises either from the 

 cosliac (c) or the adrenolumbalis (^c) and passes to the dia- 

 phragm, near its dorsal border. In the diaphragm it passes 

 ventrad, lying at the medial margin of the costal portion of the 

 diaphragm, as far as its sternal portion, where it unites with the 

 artery of the opposite side. The two thus form an arch, from 

 which radiating arteries pass off to supply the diaphragm. 



4. A. renalis (^). — The two renal arteries arise from the 

 sides of the aorta, usually at about the same point, so that the 

 left passes caudolaterad and the right craniolaterad (owing to 

 the position of the kidneys). The artery usually divides just 

 before entering the kidney (2). It passes dorsad of the vein 

 (/). The renal artery sometimes sends a branch to the supra- 

 renal body ( 1 ). It also occasionally gives origin to the sper- 

 matic artery (//). 



5. A. spermatica interna (/i). — This rises from the aorta 



