The accessory pancreatic duct empties into the duodenum just above the major duodenal papilla at the minor duodenal papilla (Fig. 4.109). If the accessory duct is followed from the minor papilla into the head of the pancreas, a branch point is discovered:
One branch continues to the left, through the head of the pancreas, and may connect with the pancreatic duct at the point where it turns inferiorly.
A second branch descends into the lower part of the head of the pancreas, anterior to the pancreatic duct, and ends in the uncinate process.
The main and accessory pancreatic ducts usually communicate with each other. The presence of these two ducts reflects the embryological origin of the pancreas from dorsal and ventral buds from the foregut.
The arterial supply to the pancreas (Fig. 4.110) includes the: gastroduodenal artery from the common hepatic artery (a branch of the celiac trunk), anterior superior pancreaticoduodenal artery from the gastroduodenal artery, posterior superior pancreaticoduodenal artery from the gastroduodenal artery, dorsal pancreatic artery from the inferior pancreatic artery (a branch of the splenic artery), great pancreatic artery from the inferior pancreatic artery (a branch of the splenic artery), anterior inferior pancreaticoduodenal artery from the inferior pancreaticoduodenal artery (a branch of the superior mesenteric artery), and posterior inferior pancreaticoduodenal artery from the inferior pancreaticoduodenal artery (a branch of the superior mesenteric artery).
The duct system for the passage of bile extends from the liver, connects with the gallbladder, and empties into the descending part of the duodenum (Fig. 4.111). The coalescence of ducts begins in the liver parenchyma and continues until the right and left hepatic ducts are formed. These drain the respective lobes of the liver.
The two hepatic ducts combine to form the common hepatic duct, which runs near the liver, with the hepatic artery proper and portal vein in the free margin of the lesser omentum.
As the common hepatic duct continues to descend, it is joined by the cystic duct from the gallbladder. This completes the formation of the bile duct. At this point, the bile duct lies to the right of the hepatic artery proper and usually to the right of, and anterior to, the portal vein in the free margin of the lesser omentum.
The omental foramen is posterior to these structures at this point.
The bile duct continues to descend, passing posteriorly to the superior part of the duodenum before joining with the pancreatic duct to enter the descending part of the duodenum at the major duodenal papilla (Fig. 4.111).
The spleen develops as part of the vascular system in the part of the dorsal mesentery that suspends the developing stomach from the body wall. In the adult, the spleen lies against the diaphragm, in the area of rib IX to rib X (Fig. 4.112). It is therefore in the left upper quadrant, or left hypochondrium, of the abdomen.
The spleen is connected to the: greater curvature of the stomach by the gastrosplenic ligament, which contains the short gastric and gastro-omental vessels; and left kidney by the splenorenal ligament (Fig. 4.113), which contains the splenic vessels.
Both these ligaments are parts of the greater omentum.
The spleen is surrounded by visceral peritoneum except in the area of the hilum on the medial surface of the spleen (Fig. 4.114). The splenic hilum is the entry point for the splenic vessels, and occasionally the tail of the pancreas reaches this area.
The arterial supply to the spleen (Fig. 4.115) is the splenic artery from the celiac trunk.