THE EENAL AND SPERMATIC AETEEIES. 433 



aorta, about 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 accom- 

 panying renal veins. Previously to reaching the concave border of the 

 kidney, each artery divides into fuur 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 distri- 

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

 structure of that organ. 



Branches. — The renal artery, before passing into the glandular substance, 

 furnishes a small branch to the suprarenal capsule, a second to the ureter, and 

 several others which ramify in the connective tissue and fat behind the 

 kidney. 



Varieties. —The o-enal artery may be replaced by two, three, four, or even five 

 branches ; and the gi-eatest 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 suc- 

 cession from the aorta itself, it would seem as if the deviation were merely an 

 increased degree of that in which the renal arteiy 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 foiind 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 bifiu'cation ; or from 

 the left common iliac at its origin. 



The branches of the renal artery, instead of entering at the hilus, sometimes 

 reach and penetrate the gland near its upper end, or on its anterior surface. 

 The right renal artery has been seen to cross the vena cava in front instead of 

 behind. Supernumerary branches are also frequently found. The most common 

 are, the diaphragmatic from the inferior suprarenal ; a hepatic branch from the 

 right renal ; branches to the small and large intestines ; the middle suprarenal ; 

 the spermatic, and various lumbar arteries. Lastly, cases occui", though very 

 rai"ely, in which one of the renal arteries is wanting. 



Spermatic and ovarian arteries. — The spermatic arteries, two 

 small and very long vessels, arise close together from the fore part of 

 the aorta a little below the renal arteries. Each artery is directed down- 

 wards 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, passes 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. 



In the female, the ovarian arteries, corresponding to the spermatic 

 arteries in the male, are shorter than these vessels, and do not pass out 

 of the abdominal cavity. The origin, direction, and connections of the 

 ovarian artery in the first part of its course are the same as in the male ; 

 but at the margin of the pelvis it inclines inwards, and running tortu- 



VOL. I. F p 



