1194 



SPLANCHNOLOGY 



network and ultimately form the venous capillaries of the liver. By the continued 

 growth and ramification of the hepatic cylinders the mass of the liver is gradually 

 formed. The original diverticulum from the duodenum forms the common bile- 

 duct, and from this the cystic duct and gall-bladder arise as a solid outgrowth which 

 later acquires a lumen. The opening of the common duct is at first in the ventral 

 wall of the duodenum; later, owing to the rotation of the gut, the opening is carried 

 to the left and then dorsalward to the position it occupies in the adult. 



As the liver undergoes enlargement, both it and the ventral mesogastrium of 

 the fore-gut are gradually differentiated from the septum transversum; and from 

 the under surface of the latter the liver projects downward into the abdominal 

 cavity. By the growth of the liver the ventral mesogastrium is divided into two 

 parts, of which the anterior forms the falciform and coronary ligaments, and the 

 posterior the lesser omentum. About the third month the liver almost fills the 

 abdominal cavity, and its left lobe is nearly as large as its right. From this period 

 the relative development of the liver is less active, more especially that of the left 

 lobe, which actually undergoes some degeneration and becomes smaller than the 

 right; but up to the end of fetal life the liver remains relatively larger than in 

 the adult. 



ep at . Hepatic 



' lc duct artery 



Orifices of intralobular veins 



FIG. 1089. Longitudinal section of a hepatic vein. 

 (After Kiernan.) 



Portion of canal 



from which 



vein hag been 



removed. 



Fio. 1090. Longitudinal section of a small portal vein 

 and canal. (After Kiernan.) 



Vessels and Nerves. The vessels connected with the liver are: the hepatic artery, the portal 

 vein, and the hepatic veins. 



The hepatic artery and portal vein, accompanied by numerous nerves, ascend to the porta, 

 between the layers of the lesser omentum. The bile duct and the lymphatic vessels descend 

 from the porta between the layers of the same omentum. The relative positions of the three 

 structures are as follows: the bile duct lies to the right, the hepatic artery to the left, and the 

 portal vein behind and between the other two. They are enveloped in a loose areolar tissue, the 

 fibrous capsule of Glisson, which accompanies the vessels in their course through the portal 

 canals in the interior of the organ (Fig. 1090). 



The hepatic veins (Fig. 1089) convey the blood from the liver, and are described on page 680. 

 They have very little cellular investment, and what there is binds their parietes closely to the 

 walls of the canals through which they run; so that, on section of the organ, they remain widely 

 open and are solitary, and may be easily distinguished from the branches of the portal vein, 

 which are more or less collapsed, and always accompanied by an artery and duct. 



The lymphatic vessels of the liver are described on page 711. 



The nerves of the liver, derived from the left vagus and sympathetic, enter at the porta and 

 accompany the vessels and ducts to the interlobular spaces. Here, according to Korolkow. the 



