Anatomy - Pancreaticoduodenectomy, pylorus-preserving, partial (OP according to Traverso)

The pancreas, composed of lobules, has a reddish-gray color, is 14 – 18 cm long, and weighs 65 – 80 grams. It is located at the level of the 1st and 2nd lumbar vertebrae and extends wedge-shaped from the epigastric region to the left hypochondriac region. Due to its developmental history, the organ is in close proximity to the upper abdominal organs and vessels.

The pancreas is enclosed by capsule-like connective or fatty tissue and is divided into three sections: head, body, and tail. While a somewhat firmer connective tissue plate is located in the posterior head area, the gland is otherwise predominantly loosely connected dorsally with the connective tissue. As a retroperitoneal organ, the gland is covered with peritoneum on its anterior surface.

The widest part of the gland is the head of the pancreas, which, located to the right of the spine, fits into the loop formed by the duodenum. Both the anterior and posterior surfaces of the duodenum can be overlapped by glandular tissue to varying degrees here. The head encompasses with its caudal part (uncinate process) from behind the superior mesenteric vein, occasionally also the artery. The groove located in the uncinate process and the remaining part of the pancreatic head is referred to as the pancreatic notch.

The part of the pancreas located at the level of the 1st lumbar vertebral body, with a width of about 2 cm, represents the transition area from the head to the body and lies over the superior mesenteric vessels. From a surgical perspective, this section is also referred to as the neck of the pancreas.

The elongated body of the pancreas runs obliquely over the 1st and 2nd lumbar vertebrae upwards, bulges ventrally into the omental bursa, and arches towards the splenic hilum, with the transition into the tail occurring without precise anatomical demarcation. Dorsal to the body, alongside the spine, are the aorta, inferior vena cava, and superior mesenteric artery and vein.

The tail of the pancreas forms the pointed continuation of the glandular body and extends to or into the splenorenal ligament.

The pancreas can be configured in various shape variants, obliquely, S-shaped, transversely, and L-shaped. A horseshoe shape and an inverted V-shape have also been described. The transitions between the shape variants are fluid.

Topographically, the pancreas has the following relationships with adjacent organs and retroperitoneally located conduits:

• ventrally, the omental bursa and the posterior surface of the stomach
• to the right, there is a close relationship between the head and the duodenal loop
• to the left, there is a close relationship to the splenic hilum
• the posterior wall of the pancreas touches at the level of the head the portal vein, the superior mesenteric artery and vein, as well as the common bile duct; at the level of the body, the splenic artery and vein, the inferior mesenteric vein, the inferior vena cava, and the abdominal aorta; at the level of the tail, the left kidney

The approximately 2 mm thick Ductus pancreaticus traverses the organ in its longitudinal extension near the posterior surface and receives numerous short glandular ducts that enter it perpendicularly along its path. In about 77% of cases, the duct joins with the Ductus choledochus at the Papilla duodeni major in the posterior wall area of the descending part of the duodenum; in the remaining cases, the openings of both ducts are close to each other. The Ductus pancreaticus accessorius, an accessory duct, is often only rudimentarily developed or completely absent. If present, it opens at the Papilla duodeni minor.

The arterial supply of the pancreas is provided by the superior pancreaticoduodenal artery, which originates from the common hepatic artery, and the head of the pancreas is additionally supplied by the inferior pancreaticoduodenal artery, which comes from the superior mesenteric artery. While the blood supply of the head is relatively constant, the body and tail have a variable vascular supply: short arteries originating from the splenic artery and branches of the transverse pancreatic artery.

The venous drainage from the head of the pancreas occurs via the superior mesenteric vein, while the body and tail belong to the drainage area of the splenic vein.

The lymphatic vessels of the pancreas run parallel to the blood vessels to all lymph nodes located in the immediate vicinity of the pancreas. The peripancreatic lymph nodes (1st station) are closely attached to the gland, sometimes even superficially present in the glandular parenchyma. At the upper edge of the organ, there is a chain of lymph nodes extending from the splenic hilum to the hepatoduodenal ligament; additional lymph nodes are located ventrally and dorsally between the pancreatic head and duodenum, at the lower edge of the pancreas, and in the caudal region. Other relevant lymph nodes are located near the celiac trunk, the superior mesenteric artery and vein, as well as on both sides of the aorta (2nd station or collecting lymph nodes).