678 ORGANS OF DIGESTION. 



.is six to one. It occupies the right hypochondrium, and is separated from the left 

 lobe, on its upper surface, by the longitudinal ligament ; on its under surface, by 

 the longitudinal fissure ; and in front, by a deep notch. It is of a quadrilateral 

 form, its under surface being marked by three fissures, the transverse fissure, 

 the fissure for the gall-bladder, and the fissure for the inferior vena cava ; and by 

 two shallow impressions, one in front (impressio collect), for the hepatic flexure of 

 the colon, and one behind (impressio renalis), for the right kidney and supra-renal 

 capsule. 



The left kbe is smaller and more flattened than the right. It is situated in the 

 epigastric and left hypochondriac regions, sometimes extending as far as the upper 

 border of the spleen. Its upper surface is convex ; its under concave surface rests 

 upon the front of the stomach ; and its posterior border is in relation with the car- 

 diac orifice of the stomach. 



The lobus quadratus or square lobe is situated on the under surface of the right 

 lobe, bounded in front by the free margin of the liver ; behind, by the transverse 

 fissure ; on the right, by the fissure for the gall-bladder ; and, on the left, by the 

 umbilical fissure. 



The lobus jSpigelii projects from the back part of the under surface of the 

 right lobe. It is bounded, in front, by the transverse fissure ; on the right, by 

 the fissure for the vena cava ; and on the left, by the fissure for the ductus 

 venosus. 



The lobus caudatus or tailed lobe is a small elevation of the hepatic substance, 

 extending obliquely outwards, from the base of the lobus Spigelii, to the under 

 surface of the right lobe. It separates the right extremity of the transverse fissure 

 from the commencement of the fissure for the inferior vena cava. 



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

 are the hepatic artery, the portal vein, the hepatic vein, the hepatic duct, and lym- 

 phatics. 



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

 lymphatic vessels and nerves, ascend to the transverse fissure, between the layers 

 of the gastro-hepatic omentum ; the hepatic duct lying to the right, the hepatic 

 artery to the left, and the portal vein behind 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, which are hollowed out of the interior 

 of the organ. 



The hepatic veins convey the blood from the liver. They commence at the cir- 

 cumference of the organ, and proceed towards the deep fossa in its posterior border, 

 where they terminate by two large, and several smaller branches, in the inferior 

 vena cava. 



The hepatic veins have no cellular investment, consequently their parietes are 

 adherent to the walls of the canals through which they run ; so that, on a section 

 of the organ, these veins remain widely open and solitary, and may be easily dis- 

 tinguished from the branches of the portal vein, which are more or less collapsed, 

 and always accompanied by an artery and duct. 



The lymphatics are large and numerous, consisting of a deep and superficial set. 

 They have been already described. 



Nerves. The nerves of the liver are derived from the hepatic plexus of the 

 sympathetic, from the pneumogastric nerves, especially the left, and from the 

 right phrenic. 



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

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

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

 invested by a fibrous and a serous coat. 



The serous coat is derived from the peritoneum, and invests the entire surface of 

 the organ, excepting at the point corresponding to the attachment of its various 

 ligaments, and at the bottom of the different fissures, where it is deficient. It is 

 intimately adherent to the fibrous coat. 



