148 THE VENA PORTtE. 



iliac receives the circumflex veins, and then blends with 

 the posterior vena cava. 



THE POSTERIOR CAVA, 



The posterior cava runs along the lumbar region, in- 

 clining to the right side {Plate IV. B) of the spine ; when 

 about to leave the loins it receives the two spermatic veins ; 

 and immediately after the lumbar veins by one trunk pour 

 their contents into the larger vessel ; close to these last the 

 right {Plate IV. F) and left renal vessels, of a large size, 

 empty their blood into the parent receptacle ; which shortly 

 afterwards passes through the top of the liver. The vena 

 cava, as it passes through the liver, is pierced by numerous 

 holes upon its lower surface ; which holes permit the re- 

 turn of the blood from the hepatic veins. Having quitted 

 the liver the vena cava passes through the right fora- 

 men of the diaphragm ; and while going through this, the 

 blood from the venous sinuses of the diaphragm is poured 

 into it. These are the last vessels that communicate with 

 the posterior cava ; which afterwards runs within its own 

 investiture of pleura to the right auricle {Fig 18 . k), where 

 it is joined by the anterior cava ; which travels above the 

 heart {Fig 18 . a), till having reached its hindermost part, 

 it bends or dips downward to gain the right auricle. 



THE VENA PORT/E. 



This vessel arises from the stomach, the pancreas and 

 intestines, &c. by capillaries ; when having ended in one 

 common trunk, it enters the liver as such a little above the 

 hepatic duct. Within the substance of the liver it again 

 divides and subdivides, and thus once more terminates in 

 capillaries ; from which last originate the hepatic veins that 

 empty their blood into the posterior vena cava. The vena 

 portte then is peculiar for originating by capillaries, running 

 by branches to one common trunk, and then dividing to 

 terminate in capillaries. It is the only vein that has 

 capillaries at both extremities; other veins originate by 

 capillaries, but terminating by means of a large trunk 

 within the heart. Besides this, the vena portae has another 

 peculiarity; it goes to the liver for secretion. All other 

 veins carry away blood only after the secretion has been 



