226 CIRCULATORY SYSTEM. 



divides into two principal trunks; one of which supplies that 

 part of the colon in the right hypochondriac region, and the 

 other the remainder of its transverse portion, forming an anas* 

 tomosis with the colica superior of the inferior mesenteric ar- 

 tery. The arteries which supply the colon differ from those 

 supplying the small intestines, in forming but one row of 

 arches; which, in fact, ate produced by the anastomoses 

 spoken of, and have, therefore, extremely large meshes. From 

 the convexity of these arches, many parallel branches run out 

 to supply the colon, and are very minutely distributed to it. 



The Capsular Arteries, the Emulgents, and the Spermatics, 

 arise from the aorta, between the superior and the inferior me- 

 senteric. But they will be described after the inferior mesen- 

 teric, so as to keep together the account of the arteries of the 

 intestines. 



The Inferior Mesenteric Artery, (Art. Mesenterica Inferior) 

 generally arises about one inch above the division of the aorta 

 into the two primitive iliacs, and is much smaller than the su- 

 perior Mesenteric. It inclines downwards to the left side, and 

 gets between the laminas of the mesocolon ; it then divides into 

 three branches, called the Left Colic Arteries, from their distri- 

 bution to the left side of the colon. From their relative situa- 

 tion to each other, they are distinguished into the Superior, the 

 Middle, and the Inferior; sometimes, however, there are but 

 two of these trunks. 



The Superior Colic (Art. Colica Sinislra Superior) goes hori- 

 zontally towards the colon in the left lumbar region; having got 

 near the intestine it divides into two branches, one of which 

 ascends to the transverse colon to form the anastomosis with 

 the Colica Media of the upper mesenteric, while the other de- 

 scends to unite with the colica media sinistra. The middle Co- 

 lic Artery (Art. Colica Sinistra Media) is sometimes a branch of 

 the superior, and is occasionally wanting; it goes towards the 

 upper part of the sigmoid flexure of the colon, and then bifur- 

 cates: one branch ascends to form by anastomosis an arch with 

 the superior colic, while the other branch descends to join the 

 lower colic artery. The Inferior Colic Artery (*Art. Colica Si^ 



