CHAP. VIL] THE CATS ORGANS OF CIRCULATION. 211 



diaphragm, of the thoracic aorta. It gives off certain noteworthy 

 branches the inferior phrenic, lumbar, ccoliac, mesenteric, supra- 

 renal, renal, and spermatic (or ovarian) arteries and then ends by 

 dividing into five parts, namely, its really posterior termination, 

 the caudal, or inferior sacral, artery, and the two internal and two 

 external iliac arteries. 



The inferior phrenic, which is exceedingly small, goes to the 

 hinder surface of the diaphragm, and gives off a branch which 

 extends along the psoas. The lumbar arteries continue on back- 

 wards, the series of intercostals quite resembling the last two of the 

 latter, which go to the lumbar region. They also give off a dorsal 

 branch, which passes upwards between the transverse processes of 

 the vertebrae. The main trunk of each runs down amidst the 

 abdominal muscles, which it supplies. The cceliac artery, or cceliav 

 axis, is a short and wide vessel which arises close to the diaphragm, 

 and quickly divides into three important visceral branches : 



A. The first of these is the coronary artery of the stomach, which 

 extends along the smaller curvature of the stomach from its 

 cardiac orifice. 



B. The second of these is the hepatic artery, which passes up- 

 wards to the transverse fissure of the liver, where it divides and 

 ramifies in the substance of the liver in the portal canals, along 

 with the portal vein and hepatic duct. 



C. The third branch of the coeliac axis is the splenic artery, which 

 extends to the left above the pancreas to the spleen, giving off, 

 however, some twigs to the cardiac surface of the stomach. 



A fourth branch may go to the right supra-renal capsule. 



The superior mesenteric artery is a very large vessel supplying the 

 whole small intestine (except the duodenum), together with the 

 coecum and first part of the large intestine. It subdivides (to go to 

 the intestine) in the folds of the peritoneum. 



The inferior mesenteric artery is very much smaller than the artery 

 last described. It passes out between the mesenteric peritoneal folds 

 to the hinder part of the large intestine. 



The capsular or supra-renal arteries, are very small. They arise, 

 one on each side, near the superior mesenteric artery, and pass 

 obliquely outwards, to organs hereafter to be described as the supra- 

 renal capsules. 



The renal arteries (Fig. 105, a) are exceedingly large, but short. 

 They are two in number, and they pass out, one on each side, 

 horizontally from the aorta, a little behind the superior mesenteric 

 artery (that of the right being a little the more posterior, and, from 

 the relation of the aorta to the spine, the longer), and go to the 

 kidneys, each dividing into four or five branches before it penetrates 

 the kidney, in the substance of which it ramifies, as will be hereafter 

 described. 



The spermatic, or ovarian arteries, are also two in number, 

 but each is very long and exceedingly slender. They arise side by 

 side, a little behind the renal arteries, from the ventral aspect of the 



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