Pancreas is both an exocrine and endocrine gland of human body. The exocrine part of the gland produces important enzymes of digestion. These enzymes play a key role in digestion of materials in the small intestine. On the other hand, the endocrine portion of the gland, commonly known as pancreatic islets or islets of Langerhans, produces the hormones insulin and glucagon. These hormones are very important for human body and play a key role in carbohydrate metabolism.
Structure of pancreas:
Pancreas is an elongated organ lying in the epigastrium and the upper left quadrant. It is situated on the posterior abdominal wall behind the peritoneum, and crosses the transpyloric plane. It is a soft and lobulated organ and for descriptive purposes, it is divided into four parts: Head, Neck, Body and Tail.
Head of the pancreas is disc shaped. Most of it lies within the concavity of the duodeunum. A part of the head extends to the left behind the superior mesenteric vessels and is called the uncinate process.
Neck is the constricted portion of the pancreas which connects the head to the body. It lies in front of the beginning of the portal vein and the origin of the superior mesenteric artery.
The body is somewhat triangular in cross section and runs upward and to the left across the midline.
The tail, which is the last part of the organ, passes forward in the splenicorenal ligament and comes in contact with the hilum of spleen.
Relations of pancreas:
(From right to left)
- Transverse colon
- Attachment of the transverse meoscolon
- Lesser sac
(From right to left)
- Bile duct
- Portal and splenic veins
- Inferior vena cava
- Origin of superior mesenteric artery
- Left psoas muscle
- Left suprarenal gland
- Left kidney
- Hilum of spleen
Ducts of pancreas:
The main duct of pancreas begins in the tail and runs the entire length of the gland to reach the second part of the duodenum. During its course through the substance of the gland, it receives numerous tributaries on the way. It opens into the second part of the duodenum in company with the bile duct on the major duodenal papilla. Occasionally, the main pancreatic duct drains separately into the duodenum and does not join the bile duct (common bile duct).
Sometimes, in addition to the main pancreatic duct, there is an additional duct present, which is called the accessory pancreatic duct. When present, it drains the upper part of the head of the gland. It drains into the duodenum, separate from the main pancreatic duct, on the minor duodenal papilla. Occasionally, it may also communicate with the main pancreatic duct.
Blood supply of pancreas:
Arterial blood to the pancreas is supplied by the splenic artery and the superior and inferior pancreatico duodenal arteries.
The veins correspond to the arteries and ultimately drain into the portal venous sytem.
Lymph drainage of pancreas:
The efferent lymph vessels from the gland first drain into the nodes situated along the arteries that supply it. Ultimately, all the lymph from the gland drains into the celiac and superior mesenteric lymph nodes.
Nerve supply to pancreas:
The gland receives both sympathetic and parasympathetic nerve fibers.