744 ORGANS OF DIGESTION. 



veins communicate with this vessel. This fissure is separated from the trans- 

 verse fissure by the lobus caudatus, and from the longitudinal fissure by the 

 lobulus Spigelii. 



Lobes. The Lobes of the liver, like the ligaments and fissures, are five in 

 number : the right lobe, the left lobe, the lobus quadratus, the lobulus Spigelii, 

 and the lobus caudatus. 



The right lobe is much larger than the left ; the proportion between them 

 being as 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 trans- 

 verse fissure, the fissure for the gall-bladder, and the fissure for the inferior 

 vena cava; and by two shallow impressions, one in front (impressio colica], for 

 the hepatic flexure of the colon ; and one behind (impressio renalis), for the right 

 kidney and suprarenal capsule. 



The left lobe 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 rela- 

 tion with the cardiac 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 lobulus Spigelii 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 lobulus Spigelii, to the 

 under surface of the right lobe. It separates the right extremity of the trans- 

 verse tissue from the commencement of the fissure for the inferior cava. 



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

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

 the lymphatics. 



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

 lymphatics 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, in the interior of the organ. 



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

 circumference 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, those 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 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, and of the ramifications of the portal vein, 



