Duodenum, Pancreas, Portal vein and arteries
This specimen shows the pancreas along with the duodenum and the related blood vessels.
The pancreas is the largest digestive gland. It is made up of both the exocrine and the endocrine parts. The exocrine part, secretes enzymes involved in the digestion of the lipids, the carbohydrates and the proteins. The endocrine part is made up of clusters of cells, known as the Islets of Langerhans, which are involved in glucose homeostasis. The Pancreas is divided into four parts, namely, the head, the neck, the body and the tail. The head of the pancreas lies within the concavity of the duodenum. Inferiorly, the head presents an Uncinate process. The uncinate process is anteriorly related to the Superior mesenteric artery and the Superior mesenteric vein. At the posterior surface of the neck, there is the formation of Portal vein, by the union of Superior mesenteric vein and the Splenic vein. The superior border of the body of pancreas is related to the Splenic artery and the posterior surface is related to the splenic vein. The tail of the pancreas reaches the hilum of spleen. It consists of several Islets of Langerhans. Therefore, during splenectomy, care should be taken to preserve the tail of pancreas.
The duodenum is the first portion of the small intestine. Its main function is digestion of the chyme from the stomach. It consists of four parts, namely, 1st part, 2nd part, 3rd part and 4th part. The head of pancreas lies in close proximity with the concavity of the duodenum produced by the first three parts. In contrast radiographs, the first part normally appears to be triangular, known as the duodenal cap. The interior of the 2nd part shows two elevations, known as the major duodenal papilla and the minor duodenal papilla. The major duodenal papilla receives the opening of the bile duct and the main pancreatic duct, whereas the minor duodenal papilla receives the opening of the minor pancreatic duct.
Superior mesenteric artery:
The superior mesenteric artery is a branch of the abdominal aorta. It enters the mesentery of the small intestine and supplies the small intestine.
Superior mesenteric vein:
The superior mesenteric vein carries the venous blood from the small intestine. It anastomoses with the Splenic vein to form the portal vein.
The portal vein is formed on the posterior surface of the neck of pancreas by the anastomosis of splenic vein and the superior mesenteric vein. It carries nutrient-rich venous blood from major part of the digestive tract, the spleen, gall bladder and the pancreas and sends it to the liver. It anastomoses with the systemic venous systems to form the portosystemic anastomoses at several sites, namely, the umbilicus, the anal canal and the lower end of the oesophagus. The normal portal pressure is around 15mm Hg. If the portal pressure exceeds 40mm Hg, then it is known as the Portal hypertension.
The splenic vein carries venous blood from the spleen. It is related to the posterior surface of the body of pancreas. At the posterior surface of neck of pancreas, it unites with the superior mesenteric vein to form the portal vein.
The splenic artery is a branch of the coeliac trunk. It passes through the hilum of spleen to supply it.