122 TOPOGRAPHICAL ANATOMY OF THE 



incisions (incisunv interlobares) that divide the organ into three lobes. 

 Between these incisions is a much shallower cleft, the umbilical fissure, 

 in which the remains of the umbilical vein may be found. 



Lobes of the liver (lobi hepatis). — The three lobes into which the 

 liver is divided are known as central, right lateral and left lateral. 

 The central lobe is the smallest. The left lateral lobe is next in point 

 of size and is simple in form. The right lateral lobe, while possessed 

 of the greatest bulk, is also distinguished by the presence of a caudate 

 process (processus caudatus) on its visceral surface. The process is 

 three-sided and tapering. Its base springs from the main mass of the 

 right lateral lobe dorsal to and immediately to the right of the porta. 

 The pointed apex of the process is directed horizontally towards the 

 right, and generally reaches the border of the liver as a whole. 



In a typical mammalian liver, such as that of the dog, a second or 

 omental process projects towards the left from that part of the right 

 lateral lobe that is dorsal to the porta. The horse dififers from the rest 

 of the domestic mammals in that the omental process is absent. 



Having recognised the subdivisions of the liver, the dissector should 

 endeavour to distinguish certain special impressions on the visceral 

 surface. This will be easy if the organ has been properly hardened 

 in situ. 



The best marked concavity has already been mentioned in con- 

 nection with the dorsal border of the gland. It is caused by the right 

 kidney (impressio renalis), and is bounded by the caudate process and 

 the most dorsal part of the right lateral lobe. The dorsal part of the 

 left lateral and central lobes carries a depression (impressio gastrica) 

 produced by the stomach. The exact extent of the concavity naturally 

 varies in accordance with the amount of gastric distension. A well- 

 marked curved groove crosses the right lateral lobe from the region of 

 the porta to the margin of the liver. This lodges the duodenum, and 

 hence is known as the duodenal impression (impressio duodenalis). 

 Ventral to the gastric and duodenal impressions is a transversely 

 elongated depression (impressio colica) produced by the dorsal 

 diaphragmatic flexure and right dorsal part of the colon. Immediately 

 ventral to the termination of the groove for the duodenum is an ill- 

 marked caecal impression (impressio caecalis) associated with, the dorsal 

 sac of the caecum. 



Ligaments of the liver. — Inasmuch as the ligaments that hold the 

 liver in position are parts of the peritoneum, it follows that they are all 

 continuous with each other and not independent structures. To 

 appreciate this it is only necessary to follow the various peritoneal 

 lines of attachment. This is perhaps best done by beginning with the 



