1732 HUMAN ANATOMY. 



even of foreign bodies which have been swallowed. Pressure from extrinsic causes is 

 far more frequent, however, as a cause of occlusion. It may be due to carcinoma of 

 the lymph-nodes in the transverse fissure, secondary to rectal or to gastric cancer ; 

 or to enlargement of the head of the pancreas from new growth or from inflammation ; 

 or to aneurism of branches of the coeliac axis. 



In these cases, contrary to what is found in occlusion from gall-stones, the gall- 

 bladder is usually enlarged. 



Congenital obliteration of the ducts may occur. 



Operatio7is on the Gall- Bladder a^id Biliary Ducts. — A vertical incision, at least 

 7.5-10 cm. (3-4 in. ) in length from the costal margin downward, made over the 

 middle of the right rectus muscle, the fibres of which are separated, will usually 

 satisfactorily expose the gall-bladder. If it is necessary to open either of the ducts, 

 the incision may be prolonged upward in the interval between the xiphoid cartilage 

 and the costal cartilages. If the liver is then drawn downward from beneath the ribs 

 and rotated upward and outward and the transverse colon is drawn downward, the 

 subhepatic space will be well exposed, bounded by the under surface of the liver above 

 and externally, the colon and transverse mesocolon below, and the duodenum and 

 pyloric end of the stomach internally. In this position, especially if a sand-bag has 

 been placed beneath the back opposite the liver, so as to push the spine forward, the 

 cystic and common ducts are brought close to the surface, the angle between them is 

 effaced, the region of entrance into the duodenum is in full view, and incision for drain- 

 age of the gall-bladder (cholecystostomy), or for the extraction of a calculus either 

 from the gall-bladder (cholelithotomy) or a duct (choledochotomy), or for the re- 

 moval of the gall-bladder (cholecystectomy) becomes possible. If there are many and 

 troublesome adhesions, the fundus and body of the gall-bladder being buried and not 

 recognizable, it is well first to locate the hepatico-duodenal fold of peritoneum, — the 

 right border of the lesser omentum, — in which the common duct may be traced from 

 its duodenal termination upward, the portal vein lying behind it and the hepatic 

 artery to the left. The cystic and hepatic ducts may then be identified. The ducts 

 may often best be examined by passing the forefinger of the left hand through the 

 foramen of Winslow, the back of the surgeon being turned towards the patient. 

 The duct, the portal vein, and the hepatic artery may thus easily be grasped between 

 the thumb and finger. The close relation of the lower end of the common duct to 

 the vena cava should be remembered in operations upon it. This portion may be 

 reached, if necessary, as in some cases of stone impacted at the duodenal papilla, 

 by opening the second portion of the duodenum and slitting up the duct as it lies in 

 the inner and posterior wall of the intestine, where it may be felt as a cord. 



The duct may be reached at a higher point by an incision through the perito- 

 neum to the right of the duodenum, the latter being freed posteriorly and drawn 

 towards the median line. 



In cases in which the common duct is permanently obstructed a portion of the 

 duodenum or jejunum may be anastomosed with the gall-bladder (cholecystenteros- 

 tomy) by direct suture. 



THE PANCREAS. 



The pancreas, the " abdominal salivary gland," lies moulded across the spinal 

 column with its head on the right, enclosed in the loop of the duodenum, and its 

 tail on the left, in contact with the spleen. It is of a light straw color running into 

 red, according to the amount of blood within the organ. The weight ranges from 

 30-150 gm. (1-5 oz.) or even more. The specific gra\'ity is about 1045. The 

 length in situ is approximately 15 cm. (about 6 in.). It consists of an enlarged 

 descending part on the right, the head, and of a long body placed transversely, 

 which is needlessly divided into tieck, body, and tail. When the organ is removed 

 from the body and straightened it somewhat resembles a revolver in shape, the head 

 being the handle. The gland, however, is so modelled by the surrounding parts 

 that its true form is seen only in its undisturbed position, or after hardening zVz situ 

 before removal from the body. 



The head (caput pancreatis) is a rounded but irregular disk packed into the 

 space between the first and third parts of the duodenum, and lying close against the 



