406 CLINICAL APPLIED ANATOMY. 



the artery and duct mostly escaping, in consequence the cirrhotic 

 process is believed to be more intimately associated with the 

 vein than with the artery or duct. The new fibrous tissue is 

 permeated by branches of the hepatic artery, and that vessel 

 becomes enlarged. The portal vein is also enlarged as the result 

 of the obstruction. The portal congestion may be considerably 

 relieved by the opening up of communications which exist between 

 the portal and general venous systems (Fig. 47, p. 338) or by 

 operative measures designed to the same end. Portal radicles 

 anastomose freely with the retroperitoneal venous plexus, and this 

 in turn communicates with the lumbar and renal tributaries to 

 the inferior vena cava. The anastomosis between the two systems 

 takes place behind the pancreas, duodenum, and colon, where 

 these are directly applied to the posterior abdominal wall without 

 the intervention of the peritoneum. Communications also occur 

 between the same systems in the roots of the various mesenteries. 

 A plexus of tortuous veins may often be found between the 

 layers of the coronary ligaments of the liver, communicating on 

 the one hand with the veins of the liver and on the other with the 

 phrenic and intercostal tributaries to the azygos veins. Some 

 small veins which are constantly present descend from the left 

 division of the portal vein along the round ligament to the um- 

 bilicus and there form connexions with the epigastric veins and 

 the superficial veins of the abdominal wall. When these veins 

 are much enlarged the venous circle of the umbilicus becomes 

 engorged, giving rise to the snake-like appearance known as the 

 caput Medusce. A venous hum may at times be heard between 

 the umbilicus and the liver, and is attributed to enlargement of 

 the veins descending from the liver. At the cardiac end of the 

 stomach the gastric tributaries to the portal system anastomose 

 with the oesophageal tributaries to the azygos veins, and these 

 communications may become enlarged and varicose. At the 

 lower end of the intestinal tract the portal system effects another 

 communication with the systemic veins, for the superior hsemor- 

 rhoidal tributary to the inferior mesenteric vein joins the middle 

 and inferior haemorrhoidal tributaries to the internal iliac veins. 



