CHAPTER 5
Pancreas: anatomy and structural anomalies

Kazuki N. Sugahara and John A. Chabot

Columbia University Irving Medical Center, New York, NY, USA

Recent imaging technologies, such as computed tomography using thin‐cut triple‐phase pancreatic protocols and magnetic resonance imaging combined with cholangiopancreatography, have greatly increased our understanding of pancreatic anatomy. As a result, major advancement has been made in interventional gastroenterology and radiology technologies and surgical techniques, which have significantly broadened our knowledge of the biological functions, histological features, and disease processes of the pancreas, and the approaches to treat various pancreatic diseases.

Pancreatic development begins during the fourth week of gestation from two primordial anlagen (initial clustering of embryonic cells) associated with the duodenum (Figure 5.1). The dorsal pancreatic bud, destined to form a portion of the pancreatic head and all of the body and tail of the pancreas, enlarges more rapidly and extends into the dorsal mesentery. The ventral pancreatic bud, the source of the uncinate process and a portion of the pancreatic head, develops in association with the hepatic rudiment and biliary ductal structures. Rotation of the ventral pancreatic bud to the left of the duodenum brings it below the dorsal bud. Fusion occurs in the seventh week of gestation. In most instances, fusion of the ventral duct with the dorsal duct results in formation of a single pancreatic duct that empties through the ventral ductal segment (Figure 5.2). Failure of ductal fusion results in formation of the congenital anomaly called pancreas divisum (Figures 5.3 and 5.4).

The pancreas is an elongated organ (12–20 cm in length in adults) that lies transversely in the upper retroperitoneum. The gland may be divided arbitrarily into head, uncinate process, neck, body, and tail (Figure 5.5). The head of the pancreas lies on the right in the concavity of the duodenal sweep. The head of the gland also is related to the gastroepiploic foramen, the right kidney, the inferior vena cava, and the right portion of the transverse mesocolon (Figures 5.6 and 5.7). The distal common bile duct traverses the head of the pancreas before entering the duodenum.

The neck of the pancreas is bordered inferiorly by both the transverse mesocolon and the root of the mesentery of the small intestine. Posteriorly, the neck of the pancreas is associated with the confluence of the superior mesenteric and splenic veins, which together form the portal vein (Figure 5.8). The body and tail of the pancreas are related, along the superior border, to the splenic artery and vein (Figure 5.9). The transverse mesocolon is attached to the inferior border of the tail of the pancreas; the stomach contacts the anterior surface. The tail of the pancreas extends to the left in the leaves of the splenorenal ligament to the hilum of the spleen. Some of these anatomical relations, as seen with cross‐sectional imaging, are shown in Figure 5.10. The arterial blood supply of the pancreas is derived from both the celiac axis and the superior mesenteric artery. Venous drainage is entirely via the portal vein.

The pancreas is a mixed endocrine and exocrine gland (Figure 5.11

Only gold members can continue reading. Log In or Register to continue