GALL-BLADDER. 525 



" active congestion" of the liver, and very commonly attends disease of the 

 heart and lungs. 



These are instances of partial congestion^ but there is sometimes general 

 congestion of the organ. u In general congestion the whole liver is of a 

 red colour, but the central portions of the lobules are usually of a deeper 

 hue than the marginal portions." 



GALL-BLADDER. 



The Gall-bladder (fig. 166) is the reservoir of the bile ; it is a pyriform 

 sac, situated in a fossa on the under surface of the right lobe of the liver, 

 and extending from the right extremity of the transverse fissure to the free 

 margin. It is divided into a body, fundus, and neck : the fundus or broad 

 extremity in the natural position of the liver is placed downwards, and 

 frequently projects beyond the free margin of the liver, while the neck, 

 small and constricted, is directed upwards. This sac is composed of three 

 coats, serous, fibrous, and mucous. The serous coat is partial, is derived 

 from the peritoneum, and covers that side only which is unattached to the 

 liver. The middle or fibrous coat is a thin but strong fibrous layer, con- 

 nected on one side to the liver, and on the other to the peritoneum. The 

 internal or mucous coat is but loosely attached to the fibrous layer ; it is 

 everywhere raised into minute rugae, which give it a beautifully reticulated 

 appearance, and forms, at the neck of the sac, a spiral valve. It is con- 

 tinuous through the hepatic duct with the mucous membrane lining all the 

 ducts of the liver, and through the ductus communis choledochus, with 

 the mucous membrane of the alimentary canal. 



The Biliary ducts are, the ductus communis choledochus, the cystic, 

 and the hepatic duct. 



The Ductus communis choledochus (x^ 1 ? bilis, <5^ofAi recipio) is the 

 common excretory duct of the liver and gall-bladder ; it is about three 

 inches in length, and commences at the papilla situated on the inner side 

 of the cylinder of the perpendicular portion of the duodenum. Passing 

 obliquely between the mucous and muscular coat, it ascends behind the 

 duodenum, and through the right border of the lesser omentum ; and 

 divides into two branches, the cystic duct and the hepatic duct. It is 

 constricted at its commencement in the duodenum, and becomes dilated 

 in its progress upwards. 



The Cystic duct, about an inch in length, passes outwards from the 

 preceding to the neck of the gall-bladder, with which it is continuous. 



The Hepatic duct continues onwards to the transverse fissure of the liver, 

 and divides into two branches, which ramify through the portal canals to 

 every part of the liver. 



The coats of the hepatic ducts are an external or fibrous, and an internal 

 or mucous coat. The external coat is composed of a contractile fibrous 

 tissue, which is probably muscular ; but its muscularity has not yet been 

 demonstrated in the human subject. The mucous coat is continuous on 

 the one hand with the lining membrane of the hepatic . ducts and gall 

 bladder, and on the other with that of the duodenum. 



Vessels and Nerves. The gall-bladder is supplied with blood by the 

 cystic artery, a branch of the hepatic. Its veins return their blood into 

 the portal vein. The nerves are derived from the hepatic plexus. 



