3o6 THE CIRCULATORY SYSTEM. 



on each side at about the level of the caudal ends of the kidneys, 

 and passes laterad (or it may arise from the renal). In male 

 specimens the artery turns caudad, along with the correspond- 

 ing vein {it), and passes to the inguinal canal. Thence it 

 passes along with the vas deferens and the vein (forming 

 all together the spermatic cord) to the testes and the other 

 structures in the scrotum. 



In females (Fig. ii2, 2, page 265) the artery is larger and 

 passes more nearly directly laterad, being much convoluted. 

 It passes to the ovary, being now called the ovarian artery. 

 •It sends branches into the ovary (r) and to the cranial end of 

 the uterus (/) ; the latter anastomosing with branches of the 

 uterine artery (3). 



6. A. mesenterica inferior (Fig. 126, /). — The inferior me- 

 senteric artery has its origin from the aorta at about the level of 

 the last lumbar vertebra. It passes toward the large intestine, 

 and near it divides into two branches, the colica sinistra, 

 which passes craniad along the descending colon, anastomos- 

 ing with the colica media, and the superior hemorrhoidal, 

 which passes caudad along the descending colon and rectum 

 and anastomoses with the middle hemorrhoidal (page 308). 



7. A. iliolumbalis (Fig. 126,7').^ — The iliolumbar arteries 

 arise from the aorta about two centimeters caudad of the inferior 

 mesenteric and pass laterad over the ventral surface of the psoas 

 minor and iliopsoas muscles. Each divides into two main 

 branches, one passing caudad and the other craniad ; these 

 supply the muscles of this region. The cranial branch anas- 

 tomoses with branches of the adrenolumbalis (r). The caudal 

 branch sends an artery through the abdominal wall to appear 

 at the cranial edge of the thigh ; it passes onto the lateral sur- 

 face of M. sartorius and extends here some distance distad. 



8. A. lumbalis. — There are usually seven pairs of lumbar 

 arteries, passing almost directly dorsad from the dorsal surface 

 of the aorta ; the first pair arising just craniad of the diaphragm, 

 the last at the same level as the origin of the external iliac. 

 The two arteries of a pair usually arise from the aorta one 

 behind the other, or they may arise by a common trunk. 

 They correspond to the intercostal arteries. They pass 



