384 THE LIVER. 



and is entirely covered by the ribs, except a small portion opposite the 

 substernal notch. AG:ain, during a deep inspiration, the liver descends 

 below the ribs, and in expiration retires upwards behind them. In 

 females it is often permanently forced downwards below the costal car- 

 tilages, owing to the use of tight stays ; sometimes it reaches nearly as 

 low as the crest of the ilium ; and, in many such cases, its convex 

 surfrice is indented from the pressure of the ribs. 



To the left of the longitudinal fissure the liver is in cor\tact with the 

 pyloric extremity and anterior surface of the stomach, on which it 

 moves freely. When the stomach is quite empty, the left part of this 

 surface of the liver may overlap the cardiac end of that viscus. To the 

 right of the longitudinal fissure the liver rests upon the first part of 

 the duodenum and the hepatic flexure of the colon. Farther back it is in 

 contact with the r.jiper part of the right kidney and suprarenal capsule. 

 Vessels and Nerves. — The two vessels by which the liver is sup- 

 plied with blood are the hepatic artery and the vena porta?. The lie- 

 patic artery (tig. 273, 14), a branch of the coeliac axis, is small in com- 

 parison with the organ to which it is distributed. It enters the trans- 

 verse fissure, and there divides into a right and left branch, for the two 

 principal lobes. 



By far the greater part of the blood which passes through the liver, — 

 and in this respect it differs from all other organs of the human body, — 

 is conveyed to it by a large vein, the vena ports (fig. 273, 15). .This 

 vein is formed ])y the union of the veins of the stomach, intestines and 

 omenta as well as those of the pancreas and spleen, and also those from 

 the gall-bladder. It enters the transverse fissure, or porta, and, like the 

 he])atic artery, divides into two principal branches. 



The hepatic artery and portal vein, lying in company with the bile- 

 duct, ascend to the liver between the layers of the gastro-hepatic 

 omentum, above the foramen of AVinslow, and thus reach the transverse 

 fissure. In this course the bile-duct is to the right, the hepatic 

 artery to the left, and the large portal vein behind the other two. They 

 are accompanied by numerous lymphatic vessels and nerves. The 

 branches of these three vessels accompany one another in their course 

 through the liver nearly to their termination ; and are surrounded for 

 somxc "distance by a common areolar investment (Glisson's capsule), 

 which is prolonged into the interior of the organ. 



The hepatic veins, which convey the blood away from the liver, 

 pursue through its substance an entirely different course from the other 

 vessels, and pass out at its posterior border, where, at the bottom of the 

 fossa already described, they end by two or three principal branches, 

 besides a number of smaller ones, in the vena cava inferior. 



The lymphatics of the liver, large and numerous, form a deep and 



a superficial set. Their mode of origin and distribution will be after- 

 wards described. 



The nerves arc derived partly from the coeliac plexus, and partly 



from the pneumogastric nerves, especially from the left pneumogastric. 



Tliey enter the liver supported by the hepatic artery and its branches ; 



along with which they may be traced a considerable way in the portal 



canals, but their ultimate distribution is not known. 



Excretory Apparatus. — The excretory apparatus of the liver 



consists of the hepatic duct, the cystic duct, the gall-bladder, and the 



common bile-duct. 



