GALL-BLADDER. 747 



The Hepatic Veins commence in the interior of each lobule by a plexus, the 

 branches of which converge to form the intralobular vein. 



The intralobular vein passes through the centre of the lobule, and leaves it at 

 its base to terminate in a sublobular vein. 



The sublobular veins unite with neighboring branches to form larger veins ; 

 and these join to form the large hepatic trunks, which terminate in the vena 

 cava. 



GALL-BLADDER. 



The Gall-bladder is the reservoir for the bile; it is a conical or pear-shaped 

 membranous sac, lodged in a fossa on the under surface of the right lobe of the 

 liver, and extending from near the right extremity of the transverse fissure to 

 the anterior free margin of the organ. It is about four inches in length, one 

 inch in breadth at its widest part, and holds from eight to ten drachms. It is 

 divided into a fundus, body, and neck. The fundus, or broad extremity, is 

 divided downwards, forwards, and to the right, and occasionally projects from 

 the anterior border of the liver: the body and neck are directed upwards and 

 backwards to the left. The gall-bladder is held in its position by the perito- 

 neum, which, in the majority of cases, passes over its under surface, but the 

 serous membrane occasionally invests the gall-bladder, which then is connected 

 to the liver by a kind of mesentery. 



Relations. The body of the gall-bladder is in relation, by its upper surface, 

 with the liver, to which it is connected by areolar tissue and vessels; by its 

 under surface, with the first portion of the duodenum, occasionally the pyloric 

 end of the stomach, and the hepatic flexure of the colon. The fundus is com- 

 pletely invested by peritoneum ; it is in relation, in front, with the abdominal 

 parietes, immediately below the tenth costal cartilage ; behind with the trans- 

 verse arch of the colon. The neck is narrow, and curves upon itself like the 

 italic letter/; at its point of connection with the body and with the cystic duct, 

 it presents a well-marked constriction. 



When the gall-bladder is distended with bile or calculi, the fundus may be felt through the 

 abdominal parietes, especially in an emaciated subject ; the relations of this sac will also serve 

 to explain the occasional occurrence of abdominal biliary fistulae, through which biliary calculi 

 may pass out, and of the passage of calculi from the gall-bladder into the stomach, duodenum, 

 or colon, which occasionally happens. 



Structure. The gall-bladder consists of three coats; serous, fibrous and mus- 

 cular, and mucous. 



The external or serous coat is derived from the peritoneum; it completely 

 invests the fundus, but covers the body and neck only on their under surface. 



The middle or fibrous coat is a thin but strong fibrous layer, which forms the 

 framework of the sac, consisting of dense fibres which interlace in all directions. 

 Plain muscular fibres are also found in this coat, disposed chiefly in a longitu- 

 dinal direction, a few running transversely. 



The internal or mucous coat is loosely connected with the fibrous layer. It is 

 generally tinged with a yellowish-brown color, and is everywhere elevated into 

 minute rugse, by the union of which numerous meshes are formed; the de- 

 pressed intervening spaces having a polygonal outline. The meshes are smaller 

 at the fundus and neck, being most developed about the centre of the sac. 

 Opposite the neck of the gall-bladder, the mucous membrane projects inwards 

 so as to form a large valvular fold. 



The mucous membrane is covered with columnar epithelium, and secretes an 

 abundance of thick viscid mucus; it is continuous through the hepatic duct 

 with the mucous membrane lining the ducts of the liver, and through the duc- 

 tus communis choledochus with the mucous membrane of the alimentary canal. 



The Biliary Ducts are, the hepatic, the cystic, and the ductus communis 

 choledochus. 



The hepatic duct is formed of two trunks of nearly equal size, which issue 

 from the liver at the transverse fissure, one from the right, the other from the 



