THE VISCERAL BRANCHES. 805 



nal aorta or from the middle sacral, the common iliac, the internal iliac, or the inferior mesen- 

 teric, and occasionally the renal artery proper may be lacking and its place taken by a vessel 

 from one or other of these origins. These accessory arteries frequently enter the substance of 

 the kidney elsewhere than at the hilum. 



The two renal arteries may arise by a common trunk from the anterior surface of the aorta, 

 and they occasionally give off branches which are either accessory to or replace vessels normally 

 arising elsewhere. Thus they have been observed to give rise to the inferior phrenics, the right 

 branch of the hepatic, the spermaticS; branches to the pancreas and colon, and one or more of 

 the lumbar arteries. 



ia. The Spermatic Arteries. — The spermatic arteries (aa. spermaticae internae) 

 (Figs. 718, 1591) are two slender vessels which arise from the anterior surface of the 

 aorta a little below the renals. They are directed downward, and slightly outward and 

 forward, towards the lower part of the anterior abdominal wall, and as they approach 

 this each vessel curves inward towards the median line to reach the internal abdominal 

 ring. Here it comes into relation with the vas deferens and becomes enclosed with 

 it in the spermatic cord. Embedded in this structure, it traverses the inguinal canal 

 and passes into the scrotum, terminating just above the testis by dividing into 

 branches which pass to that organ and to the epididymis. 



Relations. — In its course through the abdomen the left spermatic artery lies 

 behind the peritoneum and rests upon the psoas muscle. About the middle of this 

 portion of its course it crosses obliquely in front of the ureter, and lower down has 

 resting upon it the sigmoid colon. The right artery at first lies in the root of the 

 mesentery ; it descends obliquely upon the anterior surface of the inferior vena cava 

 and then, crossing the ureter obliquely, comes to lie behind the terminal portion of 

 the ileum and frequently behind the vermiform appendix. 



In the pelvic and inguinal portions of their course the relations of both arteries 

 are the same. The vessels rest upon the psoas muscle to the outer side of the ex- 

 ternal iliac artery, and cross the lower part of that vessel and the accompanying vein 

 to reach the internal abdominal ring. In their course down the spermatic cord the 

 arteries lie behind the anterior group of the spermatic veins and in front of the vas 

 deferens. 



Branches. — In addition to the terminal (a) testicular and [b) epididymal branches, each 

 spermatic artery gives of? — 



(c) An ureteral branch which is distributed to the middle portion of that duct, anastomosing 

 with the ureteral branch of the renal artery above and with branches from the inferior vesical 

 artery below. 



{d) Cremasteric branches are given ofT in the course through the spermatic cord and sup- 

 ply the cremaster muscle, anastomosing with the cremasteric branch of the deep epigastric 

 artery. 



Variations. — The spermatic arteries occasionally arise by a common trunk, or, on the 

 other hand, they may arise at different levels. They have -been observed to arise from the 

 renals, especially the left one, from the suprarenals, or from the superior mesenteric artery. 



']b. The Ovarian Arteries. — The ovarian arteries (aa. ovaricae) (Fig. 726) 

 correspond in the female to the spermatic arteries of the male, and have a similar 

 origin and similar relations in the abdominal portion of their course. Arrived at 

 the pelvis, however, they cross the common iliac arteries and veins and, traversing 

 the suspensory ligament of the ovary, pass mward between the folds of the broad 

 ligament of the uterus, terminating beneath the ovary by inosculating with the uterine 

 artery. 



Branches. — Like the spermatic arteries, the ovarian give off («■) ureteral branches. In ad- 

 dition, they give rise to {b') tubal branches, which pass to the distal portions of the Fallopian 

 tubes ; (c) ligamentous branches, which accompany and supply the round ligament of the 

 uterus ; and {d ) ovarian branches, which enter the hilum of the ovary and are distributed to its 

 substance. 



8. The Lumbar Arteries. — The lumbar arteries (aa. lumbales) (Fig. 718) are 

 arranged in four pairs, and take origin from the sides of the abdominal aorta, opposite 

 the four upper lumbar vertebrae. They are directed outward upon the bodies of the 

 vertebrae, the lumbar portion of the sympathetic cord descending in front of them, and 



