PHRENIC LUMBAR. 505 



colon. On reaching the margin of the pelvis, each vessel passes in front of the 

 corresponding external iliac artery, and takes a different course in the two sexes. 



In the male, it is directed outwards, to the internal abdominal ring, and 

 accompanies the other constituents of the spermatic cord along the spermatic 

 canal to the testis, where it becomes tortuous, and divides into several branches, 

 two or three of which accompany the vas cleferens, 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. 



In the female, the spermatic arteries (ovarian) are shorter than in the male, 

 and do not pass out of the abdominal cavity. On arriving at the margins of 

 the pelvis, each artery passes inwards, between the two laminas 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 offsets are continued 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 lie by the side of the spine, 

 below the kidneys, the spermatic arteries are short ; but as these organs descend 

 from the abdomen into the scrotum, the arteries become gradually lengthened. 



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 

 below the cceliac 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 upwards and outwards upon its under surface. The left phrenic 

 passes behind the ossophagus, and runs forwards on the left side of the oeso- 

 phageal opening. The right phrenic passes behind the liver and 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 forwards to the front of the thorax, sup- 

 plying the Diaphragm, and anastomosing with its fellow of the opposite side, 

 and with the musculo-phrenic, a branch of the internal mammary. The exter- 

 nal branch passes towards the side of the thorax, and inosculates with the in- 

 tercostal arteries. The internal branch of the right phrenic gives off a few 

 vessels to the inferior vena cava; and the left one some branches to the oeso- 

 phagus. Each vessel also sends capsular branches to the suprarenal capsule 

 of its own side. The spleen on the left side, and the liver on the right, also 

 receives a few branches from these vessels. 



LUMBAR ARTERIES. 



The Lumbar Arteries are analogous to the intercostal. They are usually 

 four in number on each side, and arise from the back part of the aorta, nearly 

 at right angles with that vessel. They pass outwards and backwards, around 

 the sides of the body of the corresponding lumbar vertebra, behind the sympa- 

 thetic nerve and the Psoas muscle ; those on the right side being covered by 

 the inferior vena cava, and the two upper ones on each side by the crura of the 

 Diaphragm. In the interval between the transverse processes of the vertebra} 

 each artery divides into a dorsal and an abdominal branch. 



The dorsal branch gives off, immediately after its origin, a spinal branch, which 

 enters the spinal canal; it then continues its course backwards, between the 

 transverse processes, and is distributed to the muscles and integument of the 

 back, anastomosing with each other, and with the posterior branches of the 

 intercostal arteries. 



