938 THE ORGANS OF DIGESTION. 



nary ligament consists of two layers, which are continuous on each side with the 

 lateral ligaments ; and, in front, with the falciform ligament. Between the layers 

 a large triangular area is left uncovered by peritoneum, and is connected to the 

 Diaphragm by firm areolar tissue. 



The round ligament (ligamentum teres) is a fibrous cord resulting from the 

 obliteration of the umbilical vein. It ascends from the umbilicus, in the free 

 margin of the falciform ligament, to the notch in the anterior border of the liver, 

 from which it may be traced along the longitudinal fissure on the under surface of 

 the liver ; on the posterior surface it is continued as the obliterated ductus venosus 

 as far back as the inferior vena cava. 



Vessels. The vessels connected with the liver are also five in number : they 

 are, the hepatic artery, the portal veins, the hepatic vein, the hepatic duct, and 

 the lymphatics. 



The hepatic artery and portal vein, accompanied by numerous lymphatics and 

 nerves, ascend to the transverse fissure between the layers of the gastro-hepatic 

 omentum. The hepatic duct, lying in company with them, descends from the 

 transverse fissure between the layers of the same omentum. The relative position 

 of the three structures is as follows : the hepatic 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 capsule of Glisson, which accompanies 

 the vessels in their course through the portal canals in the interior of the organ. 



The hepatic veins convey the blood from the liver. They commence in the 

 substance of the liver, in the capillary terminations of the portal vein and hepatic 

 artery ; these tributaries, gradually uniting, usually form three veins, which con- 

 verge toward the posterior surface of the liver and open into the inferior vena 

 cava, while that vessel is situated in the groove at the back part of this organ. 

 Of these three veins, one from the right and another from the left lobe open 

 obliquely into the vena cava ; that from the middle of the organ and lobus Spigelii 

 having a straight course. 



The hepatic veins have very little cellular investment ; what there is binds 

 their parietes closely to the walls of the canals through which they run ; so that, 

 on section of the organ, these veins remain widely open and 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 hepatic veins are 

 destitute of valves. 



Structure. The substance of the liver is composed of lobules held together by 

 an extremely fine areolar tissue, and of the ramifications of the portal vein, hepatic 

 duct, hepatic artery, hepatic veins, lymphatics, and nerves, the whole being 

 invested by a serous and a fibrous coat. 



The serous coat is derived from the peritoneum, and invests the greater part 

 of the surface of the organ. It is intimately adherent to the fibrous coat. 



The fibrous coat lies beneath the serous investment and covers the entire sur- 

 face of the organ. It is difficult of demonstration, excepting where the serous 

 coat is deficient. At the transverse fissure it is continuous with the capsule of 

 Glisson, and on the surface of the organ with the areolar tissue separating the 

 lobules. 



The lobules form the chief mass of the hepatic substance ; they may be seen 

 either on the surface of the organ or by making a section through the gland. 

 They are small granular bodies about the size of a millet-seed, measuring from 

 one-twentieth to one-tenth of an inch in diameter. In the human subject their 

 outline is very irregular, but in some of the lower animals (for example, the pig) 

 they are well-defined, and when divided transversely have a polygonal outline. 

 If divided longitudinally they are more or less foliated or oblong. The bases of 

 the lobules are clustered round the smallest radicles (sublobular) of the hepatic 

 veins, to which each is connected by means of a small branch which issues from 

 the centre of the lobule (intralobular). The remaining part of the surface of each 

 lobule is imperfectly isolated from the surrounding lobules by a thin stratum of 



