476 VEINS. 



tion of the duodenum, the pancreas, portal vein, and the posterior border of th? 

 liver, which partly and occasionally completely surrounds it ; behind, it rests upon 

 the vertebral column, the right crus of the Diaphragm, the right renal and lumbar 

 arteries ; on the left side, it is in relation with the aorta. It receives in its course 

 the following branches : 



Lumbar. Supra-renal. 



Eight spermatic. Phrenic. 



Renal. Hepatic. 



Peculiarities of Position. This vessel is sometimes placed on the left side of the aorta, as 

 high as the left renal vein, after receiving which it crosses over to its usual position on the right 

 side ; or it may be placed altogether on the left side of the aorta, as far upwards as its termination 

 in the heart : in such cases, the abdominal and thoracic viscera, together with the great vessels, 

 are all transposed. 



Peculiarities of Termination. Occasionally the inferior vena cava joins the right azygos vein, 

 which is then of large size. In such cases, the superior cava receives the whole of the blood from 

 the body before transmitting it to the right auricle, the blood from the hepatic veins excepted, 

 these vessels terminating directly in the right auricle. 



The lumbar veins, three or four in number on each side, collect the blood by 

 dorsal branches from the muscles and integument of the loins, and by abdominal 

 branches from the walls of the abdomen, where they communicate with the 

 epigastric veins. At the spine, they receive branches from the spinal plexuses, and 

 they pass forwards round the sides of the bodies of the vertebrae beneath the Psoas 

 magnus, and terminate at the back part of the inferior cava. The left lumbar veins 

 are longer than the right, and pass behind the aorta. The lumbar veins commu- 

 nicate with each other by branches which pass in front of the transverse processes. 

 Occasionally two or more of these veins unite to form a single trunk, the ascending 

 lumbar, which serves to connect the common iliac, ilio-lumbar, lumbar, and azygos 

 veins of the corresponding side of the body. 



The spermatic veins emerge from the back of the testis, and receive branches 

 from the epididymis ; they form a branched and convoluted plexus, called the 

 spermatic plexus or plexus pampiniformis, below the abdominal ring. The vessels 

 composing this plexus are very numerous, and ascend along the cord in front of 

 the vas deferens ; having entered the abdomen, they coalesce to form two branches, 

 which ascend on the Psoas muscle, behind the peritoneum, lying one on each side 

 of the spermatic artery, and unite to form a single vessel, which opens on the right 

 side in the inferior vena cava, piercing this vessel obliquely ; on the left side in the 

 left renal vein, terminating at right angles with this vein. The spermatic veins 

 are provided with valves. The left spermatic vein passes behind the sigmoid 

 flexure of the colon ; this circumstance, as well as the indirect communication of 

 the vessel with the inferior vena cava, may serve to explain the more frequent 

 occurrence of varicocele on the left side. 



The ovarian veins are analogous to the spermatic in the male ; they form a 

 plexus near the ovary, and in the broad ligament and Fallopian tube, communi- 

 cating with the uterine plexus. They terminate as in the male. Valves are 

 occasionally found in these veins. These vessels, like the uterine veins, become 

 much enlarged during pregnancy. 



The renal veins are of large size, and placed in front of the divisions of the 

 renal arteries. The left is longer than the right, and passes in front of the aorta, 

 just below the origin of the superior mesenteric artery. It receives the left 

 spermatic and left inferior phrenic veins. It usually opens into the vena cava, a 

 little higher than the right. 



The supra-renal vein terminates, on the right side, in the vena cava ; on the left 

 side, in the left renal or phrenic vein. 



The phrenic veins follow the course of the phrenic arteries. The two superior, 

 of small size, accompany the corresponding nerve and artery ; the right terminating 



