THE PHRENIC ARTERIES. 557 



right. Before reaching the hilum of the kidney, each artery divides into four or 

 five branches ; the greater number of which generally lie between the renal vein 

 and ureter, the vein being in front, the ureter behind. Each vessel gives off some 

 small branches to the suprarenal capsule, the ureter, and the surrounding cellular 

 tissue and muscles. Frequently there is a second renal artery, which is given off 

 from the abdominal aorta either above or below the renal artery proper, the former 

 being the more common position. Instead of entering the kidney at the hilum, 

 these accessory renal arteries usually pierce the upper or lower part of the gland. 



The Spermatic Arteries. 



The spermatic arteries are distributed to the testes. They are two slender 

 vessels of considerable length, which arise from the front of the aorta a little below 

 the renal arteries. Each artery passes obliquely outward and downward behind 

 the peritoneum, resting on the Psoas muscle, the right spermatic lying in front of 

 the inferior vena cava, the left behind the sigmoid flexure of the colon. It then 

 crosses obliquely over the ureter and the lower part of the external iliac artery to 

 reach the internal abdominal ring, through which it passes, and accompanies the 

 other constituents of the spermatic cord along the inguinal canal to the scrotum, 

 where it becomes tortuous, and divides into several branches, two or three of 

 which accompany the vas deferens and supply the epididymis, anastomosing with 

 the artery of the vas deferens ; others pierce the back part of the tunica albuginea, 

 and supply the substance of the testis. 



The Ovarian Arteries. 



The ovarian arteries (Fig. 313) are the corresponding arteries in the female to 

 the spermatic in the male. They supply the ovaries, are shorter than the sper- 

 matic, and do not pass out of the abdominal cavity. The origin and course of the 

 first part of the artery are the same as the spermatic in the male, but on arriving 

 at the margin of the pelvis the ovarian artery passes inward, between the two 

 layers of the broad ligament of the uterus, to be distributed to the ovary. One 

 or two small branches supply the Fallopian tube ; another passes on to the side 

 of the uterus and anastomoses with the uterine arteries. Other oifsets are con- 

 tinued along the round ligament through the inguinal canal, to the integument of 

 the labium and groin. 



At an early period of foetal life, when the testes or ovaries lie by the side of 

 the spine below the kidneys, the spermatic or ovarian arteries are short ; but as 

 these organs descend from the abdomen into the scrotum or pelvis, the arteries 



O * 



become gradually lengthened. 



The Phrenic Arteries. 



The phrenic arteries are two small vessels which present much variety in 

 their origin. They may arise separately from the front of the aorta, immediately 

 above the coeliac axis, or by a common trunk, which may spring either from the 

 aorta or from the coeliac axis. Sometimes one is derived from the aorta, and the 

 other from one of the renal arteries. In only one out of thirty-six cases examined 

 did these arteries arise as two separate vessels from the aorta. They diverge from 

 one another across the crura of the Diaphragm, and then pass obliquely upward 

 and outward upon its under surface. The left phrenic passes behind the oesoph- 

 agus and runs forward on the left side of the oesophageal opening. The right 

 phrenic passes behind the inferior vena cava, and ascends along the right side of 

 the aperture for transmitting that vein. Near the back part of the central tendon 

 each vessel divides into two branches. The internal branch runs forward to the 

 front of the thorax, supplying the Diaphragm and anastomosing with its fellow of 



