512 SANGUIFEROUS SYSTEM. 



secretion of the large external deposit of adipose substance, 

 or destined to preserve the high temperature of the nervous 

 axis and other internal organs. 



On passing into the abdomen, between the crura of the 

 diaphragm, the aorta gives off from its sides, the two small 

 phrenic arteries (142. A. above r.) to the diaphragm ; two or 

 more minute supra-renals to the supra-renal capsules ; the 

 two renal arteries to the kidneys ; a pair of spermatic arteries 

 (142. A. .), to the testicles, or to their analogues the ova- 

 ries, according to the sex ; and a variable number of symme- 

 trical pairs of lumbar arteries, destined to supply the exterior 

 parietes of the abdomen, like the intercostals of the thorax. 

 The largest and most important trunks, however, arise from 

 the anterior median part of the abdominal aorta, and are the 

 caliac (142. A. r.) which sends off the coronary to the sto- 

 mach, the hepatic to the liver, and the splenic to the spleen ; 

 the superior mesenteric (142. A. s.), which arises near the 

 coeliac, and supplies the small intestine and part of the colon, 

 and the small inferior mesenteric (142. A. u.), which arises 

 near the commencement of the iliac arteries, and is distributed 

 on the colon and rectum. The direct pelvic continuation of 

 the abdominal aorta is the caudal or median sacral artery (142. 

 A. between v. w.), which, in man, and in other tail-less and 

 long-legged mammalia, forms but a small branch compared 

 with the two iliacs (142. A. v. w.), which appear to constitute 

 a bifurcation of the entire trunk ; but in the cetacea, and 

 other long-tailed species, the proportions are very different. 

 In man and a few of the higher quadrupeds, the aorta gives 

 off two large common iliac arteries (142. A. v. w.}, each of 

 which divides into an internal iliac (142. A. y. ?/.) appropriated 

 to the viscera of the pelvis, and a larger external iliac (142. A. 

 x. x.] to supply the leg ; but in most of the lower mammalia, 

 as in ruminantia, rodentia, marsupialia, carnivora, and other 

 orders, the internal iliac arteries arise separately from the 

 prolonged trunk of the aorta behind the external iliacs. 

 From the want of legs in the cetacea, they have no external iliacs. 



The internal iliac artery of each side furnishes the ilio-lunt- 

 bar branch, to the muscles of that region ; the obturator, 

 chiefly to the ilio-femoral joint and the adductor muscles of 

 the thigh; the gluteal, to the glutei and other external 

 muscles of the pelvis ; the lateral sacral, to the sacrum and 

 its exterior muscles, and to the terminal portion of the spinal 



