THORAX AND ABDOMEN OF THE HORSE 



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A. MESENTERICA CRANIALIS. — The cranial mesenteric artery is the 

 largest branch of the abdominal aorta, from the ventral border of which 

 it arises opposite the first lumbar vertebra. The artery is very short, 

 and, immediately after leaving the aorta, breaks up into branches for 

 distribution to all the intestinal tube except the commencement of the 

 duodenum, the rectum and part of the small colon. Its branches are the 

 intestinal, middle colic, dorsal colic and ileo-cjeco-colic arteries. 



Small intestine. 



Anastomotic arch. 

 Fig. 50. — To show the manner of distribution of the intestinal arteries. 



(1) Aa. intestinales. — From eighteen to twenty intestinal arteries 

 leave the cranial mesenteric close together, and run, in a radiating 

 manner, towards the small intestine between the two peritoneal layers 

 of the mesentery. Before reaching the intestine, each vessel divides 

 into two branches, and the branches of adjacent arteries anastomose. 

 Thus a series of arterial arches is formed. From the convexity of the 

 arches branches proceed to the wall of the intestine. The first intestinal 

 artery supplies a part of the duodenum and anastomoses with the 

 duodenal branch of the pancreatico-duodenal artery. The last intestinal 

 artery anastomoses with the iliac branch of the ileo-csecal artery. 



