The pancreas lies transversely along its long axis in the anterior pararenal space of the retroperitoneum. 5,6 The head of the pancreas lies within the C-loop of the second portion of the duodenum. The lateral surface of the head is against the serosa of the duodenum. The posterior surface of the head is separated from the inferior vena cava by only retroperitoneal fat and on occasion small posterior peripancreatic nodes. Medially, the head of the pancreas is closely related to the superior mes-enteric artery (SMA) and superior mesenteric vein (SMV). At the caudal portion of the head, a small portion of the pancreas extends behind the SMA and SMV, forming an uncinate process. It is connected to the SMA and SMV by small twigs of vessels that are branches of the jejunal artery and vein or that arise directly from the posterior wall of the SMA and SMV and a plexus of nerves between the head of the pancreas and the SMA. The cranial portion of the head of the pancreas is located on the right side of the SMA and SMV. As the SMV joins the splenic vein to form the portal vein, it courses behind the head of the pancreas, and from that point, extending to the left retroperitoneum, the head of the pancreas becomes the body.
The body and tail of the pancreas course transversely to the left side of the retroperitoneum toward the splenic hilum. After passing in front of the abdominal aorta and celiac axis, it curves posteriorly and in the cranial direction. In most cases, it follows the course of the splenic artery and vein, staying anterior and slightly caudal to those vessels.
Anteriorly, the pancreas is covered by posterior peritoneal layers that form the posterior wall of the lesser sac and the inframesocolic compartment of the peritoneal cavity. Just at the caudal margin along the body and tail of the pancreas, the root of the transverse mesocolon, which is formed by those two posterior peritoneal layers, merges anteriorly to suspend the transverse colon into the peritoneal cavity. The root of the transverse
Fig. 12—1. Illustration of the arterial anatomy of the pancreas.
1 = common hepatic artery; 2 = splenic artery; 3 = gastroduodenal artery; 4 = dorsal pancreatic artery; 5 = posterior superior pancreaticoduodenal artery (SPDA); 6 = anterior SPDA; 7 = inferior pancreaticoduodenal artery; 8 = superior mesenteric artery; D = duodenum.
mesocolon extends to the right, traversing across the head of the pancreas and second portion of the duodenum. The transverse mesocolon forms the inferior boundary of the lesser sac.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.