500 THE POETAL SYSTE:^! OF VEINS. 



The uterine plexus pours its blood in greatest part into the ovarian 

 veins, and is not considerable except in pregnancy. 



The dorsal vein of the penis commences by branches ■which issue 

 from the glans penis, and form in the first instance two veins, one at 

 each side of the middle line, in the dorsal groove of the penis. These 

 receive branches from the spongy body of the penis, and some super- 

 ficial veins which accompany the external pudic arteries, and proceeding 

 backwards unite and form a short trunk which enters the pelvis 

 beneath the subpubic ligament. Here it divides into two branches, 

 which are directed obliquely downwards over the prostate and the neck 

 of the bladder, and are united with the prostatic plexus. 



COMMON ILIAC VEIN. 



The common iliac vein is formed by the confluence of the external 

 and internal iliac veins. Extending from the sacro-iliac articulation 

 upwards to near the junction of the fifth with the fourth lumbar ver- 

 tebra, at a point a little to the right of the middle line, the two common 

 iliac veins unite to form the lower or ascending vena cava. The right 

 vein is shorter than the left, and is nearly vertical in its direction. The 

 right vein is placed behind, and then to the outer side of its artery ; 

 whilst the left vein is to the inner side of the left common iliac artery, 

 and then passes behind the right. These veins are destitute of valves. 



THE PORTAL SYSTEM OP VEITTS. 



The portal vein differs from other veins of the body in being sub- 

 divided into branches at both its extremities. The branches of origin, 

 by the union of which it may be said to be formed, are the veins of the 

 chylopoietic viscera, viz., the stomach, intestine, pancreas, and spleen ; 

 the other branches, or those of distribution, ramifying after the manner 

 of an artery in the substance of the liver, convey to the capillaries of 

 that organ the blood collected in the main trunk. This blood, together 

 ■with that of the hepatic artery, after having served for the secretion 

 of the bile and the nourishment of the liver, is withdrawn from that 

 organ by the hepatic veins, and carried by them into the vena cava 

 inferior. 



The portal vein or vena portae is about three inches in length. 

 Commencing at the junction of the splenic and superior mesenteric 

 veins, it passes upwards and a little to the right to reach the transverse 

 fissure of the liver. It is placed close behind the hepatic artery and the 

 bile-duct : and is surrounded by the filaments of the hepatic plexus of 

 nerves, together with numerous lymphatics. All these are imbedded in 

 loose connective tissue, and enclosed within the layers of the small 

 omentum. Within the transverse fissure it is somewhat enlarged, and 

 is there named sim/s of ihe portal vein. 



Near the right end of the transverse fissure, the vena portae divides 

 into two branches. That of the ruiht side enters directly the substance 

 of the corresponding lobe of the liver, and spreads out into branches, 

 each of which is accompanied by an offset of the hepatic artery and 

 of the hepatic duct. The left branch, which is smaller, but necessarily 

 longer, passes across to gain the left end of the transverse fissure, where 

 it enters the liver and ramifies like the preceding branch. 



