PANCEEAS. 1203 



and the hepatic artery to its left. It next descends behind and to the left of the 



superior part of the duodenum (Fig. 944), and then M Q 



between the pancreas -and descending part of the 



duodenum. Finally, it meets the pancreatic duct, and 



the two, running together, pierce the medial wall of the 



descending part of the duodenum very obliquely, and 



open by a common orifice on the papilla duodenalis 



about 3J or 4 inches (8 '7 to 10 cm.) beyond the pylorus 



(see p. 1185). 



The length of the bile-duct is about 3 inches 

 (75 mm.), and its diameter, which is very variable, is 

 generally about J inch (6 to 7 mm.). 



Structure of the Excretory Ducts. With the 



exception of the peritoneal coat, which is absent, the r 



n i jj FIG. 945. DIAGRAM SHOWING THE 

 hepatic, cystic, and bile-ducts agree with the gall-bladder BlLB AND PANCREATIC DuCT s 



in general structure. The tunica mucosa contains a large PIERCING THE WALL OF THE 

 number of mucous-producing glands, the glandulse mucosse DUODENUM OBLIQUELY. 



A.D.S., Accessory pancreatic duct 



The bile and pancreatic ducte in piercing the wall of the 



duodenum, run obliquely through its coats for about or f of muscu i ar fibr es ; M, Mucous 



an inch (12 to 18 mm.), and, as a rule, do not unite until they coat> 



have almost reached the opening on the duodenal papilla (Fig. 



945). This orifice is very much smaller than either duct, and the short and relatively wide 



common cavity which precedes it is sometimes known as the " ampulla of Vater." Occasionally 



the cystic and hepatic ducts open into the duodenum separately. 



PANCREAS. 



The pancreas is an elongated glandular mass which lies transversely on the 

 posterior abdominal wall, with its right end resting in, the concavity of the 

 duodenum (Fig. 946), and its left end touching the spleen. It secretes a 

 digestive fluid the pancreatic juice which is conveyed to the duodenum by the 

 pancreatic duct, and which constitutes one of the chief agents in intestinal digestion. 



The absence of a true capsule, and the distinct lobulation of the gland, give the 

 pancreas a very characteristic appearance (Fig. 948). 



Position. The greater part of the gland lies in the epigastrium, but the tail 

 and adjacent part of the body extend into the left hypochondrium. 



The head is placed opposite the second and upper part of the third lumbar vertebra, whilst 

 the body runs to the left, about the level of the first lumbar vertebra. It should be added, that 

 very often the inferior portion of the head projects some distance below the subcostal plane, and 

 thus lies in the umbilical region. 



In shape the pancreas, when hardened in situ, is very irregular (Fig. 946), 

 its right end being flattened and hook-like, whilst the rest of the organ is pris- 

 matic and three-sided. It may, perhaps, in general form be best compared to 

 the letter J placed thus c~, particularly if the stem and hook of the letter are 

 thickened. 



The gland is divisible into a head (caput) with a processus uncinatus, a body 

 (corpus), and a tail (cauda). The head corresponds to the hook of the c~, and 

 runs downwards and to the left along the descending and transverse portions of 

 the duodenum. The stem of the c~ represents the body of the gland, and the 

 thin left extremity of the body forms the tail. The narrow part connecting the 

 head and body is the neck (Symington). 



When removed from the body without previous hardening, the pancreas loses 

 its true form, and becomes drawn out into a slender, elongated, tongue-shaped 

 mass, with a wider end turned towards the duodenum, and a narrow end corre- 



Konding to the tail. 

 Its total length, when fixed in situ, is about 5 or 6 inches (12 '5 to 15 cm.) ; after removal, if 

 t previously hardened, it is easily extended to a length of 8 inches (20 cm.). 

 Its weight is usually about 3 ounces (87 grammes). 

 Relations. The general position and relations of the pancreas may be briefly 



