GALL-BLADDER. 681 



The sullobular 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, the broad extremity, is directed down- 

 wards, 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 peritoneum, which, in the majority 

 of cases, passes over its under surface, but it occasionally invests it, and is con- 

 nected 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 completely invested 

 by peritoneum; it is in relation, in front, with the abdominal parietes, immediately 

 below the tenth costal cartilage ; behind, with the transverse arch of the colon. 

 The neck is narrow, and curves upon itself like the Italic letter f; 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 fistula, 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 muscular, 

 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 longitudinal 

 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 ruga3, by the union of which numerous meshes are formed; the depressed 

 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 ductus 

 communis choledochus with the mucous membrane of the alimentary canal. 



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

 choledochus. 4 



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 and one from the left 

 lobe ; these unite, and pass downwards and to the right for about an inch and a 

 half to join at an acute angle with the cystic duct, to form the common choledoch 

 d uct. 



