618 THE BLOOD-VASCULAR SYSTEM. 



posterior surface of the liver, which partly and occasionally completely surrounds 

 it ; behind, with the vertebral column, the right crus of the Diaphragm, the right 

 renal and lumbar arteries, right semilunar ganglion ; on the left side, with the 

 aorta. 



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

 as high as the left renal veins, 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 upward as its ter- 

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

 vessels, are all transposed. 



Point 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, except the blood from the hepatic veins, 

 which passes directly into the right auricle. 



Tributaries. It receives in its course the following veins : 



Lumbar. Suprarenal. 



Right Spermatic. Phrenic. 



Renal. Hepatic. 



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

 tributaries from the muscles and integument of the loins and by abdominal tribu- 

 taries from the walls of the abdomen, where they communicate with the epigastric 

 veins. At the spine they receive veins from the spinal plexuses, and then pass 

 forward, round the sides of the bodies of the vertebrae beneath the Psoas magims, 

 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 are connected 

 together by a longitudinal vein which passes in front of the transverse processes of the 

 lumbar vertebrae, and is called the ascending lumbar. It forms the most frequent 

 origin of the corresponding vena azygos, and 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 tributaries 

 from the epididymis ; they unite and form a convoluted plexus called the spermatic 

 plexus (plexus pampiniformis), which forms the chief mass of the coi'd : the vessels 

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

 the vas deferens ; below the external abdominal ring they unite to form three or 

 four veins, Avhich pass along the inguinal canal, and, entering the abdomen through 

 the internal abdominal ring, coalesce to form two veins, which ascend on the Psoas 

 muscle behind the peritoneum, lying one on each side of the spermatic artery, and 

 unite to form a single vein, which opens on the right side into the inferior vena 

 cava at an acute angle ; on the left side into the left renal vein at a right angle. 

 The spermatic veins are provided with valves. 1 The left spermatic vein passes 

 behind the sigmoid flexure of the colon, and is thus exposed to pressure from the 

 contents of that bowel. 



Surgical Anatomy. The spermatic veins are very frequently varicose, constituting the 

 disease known as varicocele. Though it is quite possible that the originating cause of this 

 affection may be a congenital abnormality either in the size or number of the veins of the 

 pampiniform plexus, still it must be admitted that there are many anatomical reasons why these 

 veins should become varicose viz. the imperfect support afforded to them by the loose tissue of 

 tbe scrotum ; their great length ; their vertical course ; their dependent position ; their plexiform 

 arrangement in the scrotum, with their termination in one small vein in the abdomen ; their few 

 and imperfect valves; and tbe fact that they maybe subjected to pressure in their passage 

 through the abdominal wall. 



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 in the same way as the spermatic 

 veins in the male. Valves are occasionally found in these veins. These vessels, 

 like the uterine veins, become much enlarged during pregnancy. 



1 Rivington has pointed out that a valve is usually found at the orifices of both the right and 

 left spermatic veins. When no valves exist at the opening of the left spermatic vein into the left 

 renal vein, valves are generally present in the left renal vein within a quarter of an inch frnm 

 the orifice of the spermatic vein (Journal of Anatomy and Physiology, vol. vii. p. 103). 



