1199 



two ducts unite and open by a common orifice upon the summit of the duodenal 

 papilla, situated at the medial side of the descending portion of the duodenum, a 

 little below its middle and about 7 to 10 cm. from the pylorus (Fig. 1100). The 

 short tube formed by the union of the two ducts is dilated into an ampulla, the 

 ampulla of Vater. 



Structure. The coats of the large biliary ducts are an external or fibrous, and an .internal or 

 mucous. The fibrous coat is composed of strong fibroareolar tissue, with a certain amount of 

 muscular tissue, arranged, for the most part, in a circular manner around the duct. The mucous 

 coat is continuous with the lining membrane of the hepatic ducts and gall-bladder, and also with 

 that of the duodenum; and, like the mucous membrane of these structures, its epithelium is of 

 the columnar variety. It is provided with numerous mucous glands, which are lobulated and 

 open by minute orifices scattered irregularly in the larger ducts. 





The Pancreas (Figs. 1097, 1098). 



e pancreas is a compound racemose gland, analogous in its structures to the 

 salivary glands, though softer and less compactly arranged than those organs. 

 Its secretion, the pancreatic juice, carried by the pancreatic duct to the duodenum, 

 is an important digestive fluid. In addition the pancreas has an important internal 

 secretion, proba'bly elaborated by the cells of Langerhans, which is taken up by 

 the blood stream and is concerned with sugar metabolism. It is long and irregularly 



Rectus abdominis 



Eighth costal cartilage 



Seventh costal cartilage 



Seventh rib 



Eighth 

 rib 



Ninth 

 rib 



Tenth rib 

 > Diaphragm 



Abdominal aorta 



Twelfth rib 



Eleventh rib 



Fia. 1097. TVansverse section through the middle of the first lumbar vertebra, showing the relations of the pancreas. 



(Braune.) 



prismatic in shape; its right extremity, being broad, is called the head, and is con- 

 nected to the main portion of the organ, or body, by a slight constriction, the neck; 

 while its left extremity gradually tapers to form the tail. It is situated transversely 

 across the posterior wall of the abdomen, at the back of the epigastric and left 

 hypochondriac regions. Its length varies from 12.5 to 15 cm., and its weight from 

 60 to 100 gm. 



