LIVER. 



219 



The septum is bounded 



i.t.i. 



a lumen it is known as the hepatic duct, C,h.d. The diverticulum becomes 

 enlarged at its distal end to form the gall bladder, g.b. This has a tapering 

 neck leading to the cystic duct, c.d. After receiving the hepatic duct, the 

 diverticulum forms the common bile duct (ductus choledochus) which enters 

 the duodenum. (Just before the entrance it is joined by the pancreatic 

 duct, p.d.) 



From its development the liver is seen to be an entodermal organic 

 gland with branched and anastomosing terminal pieces. It develops in 

 the septum in close relation with the vitelline veins. Before describing the 

 structure of the adult liver the transformations of the septum and of the 

 veins should be considered. 



Transformation of the septum transversum. 

 anteriorly, that is, toward the head, by the meso- 

 thelium of the pericardium and of the pleurae. 

 Beneath the mesothelium, striated muscle 

 spreads out in the septum transversum, produc- 

 ing the diaphragm. Ventrally the septum ex- 

 tends from the liver to the subcutaneous tissue 

 of the abdominal wall; dorsally it passes from the 

 liver to the lesser curvature of the stomach and 

 the first part of the duodenum. Posteriorly, as 

 shown in Fig. 245, B, a rupture occurs through 

 it so that the cavity of the peritonaeum extends 

 from side to side between the diverticulum and 

 the small intestine. The gall bladder is thus 

 provided with a serous coat, similar to that of the 

 intestine, and it extends over the sides of the 

 liver. It forms the lateral walls of the connec- 

 tive tissue layers passing from the liver to the stomach, the 

 phragm and ventral body w r all. These connective tissue layers with their 

 mesothelial covering are mesenteric structures known as the ligaments of 

 the liver. The primary ones which represent the original septum trans- 

 versum are the falciform ligament between the liver and ventral abdominal 

 wall and diaphragm, in the median plane; the lesser omentum between the 

 liver and the duodenum and lesser curvature of the stomach, also in the 

 median plane (the blood vessels to the liver and the common bile duct are 

 within the lesser omentum) ; and finally, the right and left triangular liga- 

 ments between the liver and the diaphragm. The triangular ligaments 

 are compressed dorso-ventrally, so that their line of attachment to the 

 liver is across the body from right to left. The relation of the right tri- 

 angular ligament to the coronary ligament will be described with the 



FIG. 246. THE LEFT SIDE OF 

 AN ADULT LIVER. (Com- 

 pare with Fig. 244, B.) 



d. c., Ductus choledochus; g. b., 

 gall bladder; f. 1., falciform 

 ligament; 1. o., lesser omen- 

 tum; 1. t. 1., left triangular 

 ligament; p. v., portal vein; 

 r. 1., round ligament; v. c. i., 

 vena cava inferior. 



dia- 



