114 



GALL-BLADDER. 



side. It is a pyriform sac of about three inches in length ; its an- 

 terior extremity is globular, and called the fundus ; its posterior end 

 or fieck, is narrow, and twisted like a screw. It consists oi" three coats. 

 The external is formed of the peritoneum,* and is only a partial 

 covering for its inferior surface ; the middle® consists of a strong 

 layer of fibrous and cellular tissue ; and the internal is mucous,^ with 

 short, irregular folds, giving it a fine net-like appearance ; its colour is 

 usually that of the bile ; in the neck it is spirally twisted, and thus acts 

 as a valve. Its duct, called the cystic duct, is shorter and thinner 

 than the hepatic duct, which it joins at a very acute angle ; this 

 junction forms the ductus communis choledochus, which is about 

 the size of a goose-quill, and often three inches in length. It 

 passes through the right extremity of the pancreas at its posterior 

 portion, and perforates the duodenum obliquely and with a very 

 small orifice, through an elevated tubercle. Its artery, called cystic, is 

 a branch of the hepatic. 



PANCREAS. 



This is the largest salivary gland of the body ; it is long and 

 flat in shape, and of a light pink colour. It is placed transversely 

 behind the stomach, and in front of the last dorsal and first lumbar 

 vertebrae. It has no peritoneal covering, but is included between 



Fig. 98. 



the two laminse of the meso-colon, and extends from the curvature 

 of the duodenum'' across to the spleen.* It is about seven inches 

 long. Its right extremity^ or head, is much the thickest part, is 

 traversed by the ductus choledochus, and often called the lesser pan- 

 creas. Its left extremity gradually diminishes in breadth until it 

 touches the spleen. 



The superior edge of the pancreas has a groove for the passage 

 of the splenic artery. ^ ^ " Its structure^ like that of other 

 salivary glands, is conglomerate. Its excretory duct, called after 

 Wirsungius, is formed by a collection of small branches, which 

 come from the lobules of the gland. Its walls are thin, white, and 



