PANCEEAS. 1207 



a rather sinuous or zigzag course (Fig. 948) through the axis of the gland, at first 

 running transversely to the right, until the neck is reached, then it bends down- 

 wards into the head, approaches the descending part of the duodenum, and meets 

 the bile-duct. The two ducts pierce the medial wall of the gut obliquely (for 

 to j of an inch, 12 to 18 mm.), and open, by a common orifice on the duodenal 

 papilla, about 3J or 4 inches (8'7 to 10 cm.) beyond the pylorus (see p. 1203). 



In its course through the gland the pancreatic duct receives numerous tributaries, 

 which join it, as a rule, nearly at a right angle. The tributaries, as well as the main 

 duct itself, are easily recognised by the whiteness of their walls, which contrasts 

 with the darker colour of the gland tissue. The main duct receives tributaries from 

 all portions of the pancreas, and towards its termination attains a considerable size 

 (namely, T Vth to ^th of an inch 2'5 to 4 mm. when flattened out, or somewhat 

 larger than a crow quill). 



Superior part of duodenum 



Accessory pancreatic 

 Xduct 



Pancreatic duct ^ ^ES^fc V- Bile-duct 



Superior mesenteric artery ^' 



Superior mesenteric vein 



Head of pancreas ^||fe^^^M Branch of accessory duct 



FIG. 948. POSTERIOR ASPECT OF THE PANCREAS AND DUODENUM, with the pancreatic duct exposed. 



The superior mesenteric vessels also are shown in section, passing forwards, surrounded by the 

 recurved portion of the head of the pancreas. 



The pancreatic accessory duct (O.T. duct of Santorini) is a small and variably 

 developed duct (Fig. 948) which opens into the duodenum about J of an inch above 

 and somewhat anterior to the pancreatic duct. From the duodenum it runs to the left 

 and downwards, and soon divides into two or more branches, one of which joins the 

 pancreatic duct, the others pass down and receive tributaries from the lower part of 

 the head. It is generally supposed that the current flows from this into the main duct, 

 and not into the duodenum, as a rule, except in early life. 



Physical Characters and Structure of the Pancreas. The pancreas is of a 

 reddish cream colour, soft to the touch, and distinctly lobulated. The lobules 

 are but loosely held together by their small ducts and by loose areolar tissue ; 

 for, as already pointed out, the pancreas is devoid of a regular capsule, and 

 possesses instead merely an adventitious coat of fine connective tissue. 



The gland belongs to the class of acino-tubular glands, its alveoli or acini being 

 elongated like those of the duodenal glands ; otherwise it corresponds very closely 

 to a serous salivary gland, the general structure of which will be found on p. 1140. 

 The secretion is termed succus pancreaticus. 



Variations. The chief variations found are : (1) A separation of the part of the head, 

 known as the uncinate process, which then forms a lesser pancreas. (2) A growth of the pancreas 

 around the duodenum, which it may practically encircle for a short part of its course. And (3) 

 an opening of its duct into the duodenum, independently of the bile-duct. An accessory pancreas 

 (pancreas accessorium) is also sometimes found in the wall of the stomach or of the jejunum. 

 Diverticula of the duodenum, already described (p. 1187), ought perhaps to be mentioned in 

 this connexion. 



Vessels. The arteries of the pancreas are: (l)The superior pancreatico-duodenal, a branch 

 of the gastro -duodenal artery, which runs down on the front of the head (Fig. 946), sending branches 

 laterally to the duodenum, as well as numerous twigs into the substance of the pancreas. 

 (2) The inferior pancreatico-duodenal, a branch of the upper part of the superior mesenteric 

 artery ; or from the root of one of the rami jejunales ; it runs upwards and to the right across the 

 back of the head, and sends branches to it and to the duodenum, one of which runs between the 

 head and the duodenum. These two pancreatico-duodenal arteries anastomose around the inferior 

 border of the head. (3) Pancreatic rami from the splenic artery, are several (3 to 5) fair-sized branches 



77 b 



