414 ABDOMINAL AORTA. 



obliquely outwards upon the crura of the diaphragm to reach the supra- 

 renal capsules, to which bodies they are distributed, anastomosing at the 

 same time with the other capsular branches derived from the phrenic and 

 the renal arteries. In the foetus these arteries are of larger size. 



V. RENAL OR BMULOENT ARTERIES. 



The renal arteries, of large diameter in proportion to the size of the 

 organs which they supply, arise from the sides of the aorta, abjput half an 

 inch below the superior mesenteric artery, that of the right side being 

 rather lower down than that of the left. Each is directed outwards, so as 

 to form nearly a right angle with the aorta. In consequence of the position 

 of the aorta upon the spine, the right renal artery has to run a somewhat 

 longer course than the left, in order to reach the kidney. The artery 

 of the right side crosses behind the vena cava, and both right and left 

 arteries are overlapped by the accompanying renal veins. Previously to 

 reaching the concave border of the kidney, each artery divides into four or 

 five branches, the greater number of which usually lie intermediate between 

 the vein in front and the pelvis of the kidney behind. These branches, 

 after having passed deeply into the fissure of the kidney, subdivide and are 

 distributed in the gland, in the manner described in the account of the 

 structure of that organ. 



BRANCHES. The renal artery furnishes a small branch to the suprarenal 

 capsule, a second to the ureter, and several others which ramify in the con- 

 nective tissue and fat behind the kidney. 



PECULIARITIES. The renal artery may be replaced by two, three, four, or even five 

 branches ; and the greatest difference as to the origin of these vessels is found to exist 

 even on opposite sides of the same body. As they usually arise in succession from 

 the aorta itself, it would seem as if the deviation were merely a degree beyond that 

 in which the single artery divides into branches sooner than usual after its origin. 

 In some cases a renal artery has been seen to proceed from the common iliac ; and in 

 one case, described by Eustachius, from the internal iliac. Portal found in one 

 instance the right and left renal arteries arising by a common trunk from the fore 

 part of the aorta. In another case, one of several arteries arose from the front of the 

 aorta at its bifurcation ; or from the left common iliac at its origin. 



The branches of the renal artery, instead of entering at the hilus, may reach and 

 penetrate the gland near its upper end, or on its anterior surface. Lastly, cases occur, 

 though very rarely, in which one of the renal arteries is wanting. 



VI. SPERMATIC AND OVARIAN ARTERIES. 



The spermatic arteries, two small and very long vessels, arise close toge- 

 ther from the fore part of the aorta a little below the renal arteries. Each 

 artery is directed downwards and outwards, resting on the psoas muscle ; it 

 crosses obliquely the ureter and, afterwards, the external iliac artery, and 

 turns forward to the internal abdominal ring. There it comes into contact 

 with the vas deferens, and, separating from the peritoneum, pa-ses with the 

 other constituents of the spermatic cord along the inguinal canal, and 

 descends to the scrotum, where it becomes tortuous, and reaching the back 

 part of the testis anastomoses with the artery of the vas deferens, and finally 

 divides into branches which pierce the fibrous capsule of the testis. 



Fig. 287. VIEW OF THE ABDOMINAL AORTA AND ITS PRINCIPAL BRANCHES 

 (from Tiedernann). 



For the detailed description of this figure see p. 404 ; 6, renal arteries ; 6', 6', 

 suprarenal arteries arising from the aorta ; other suprarenal arteries are seen proceeding 



