Pancreas Anatomy

Pancreatic Overview

Introduction to the Pancreas

The pancreas is a vital organ in both the digestive system and endocrine system of vertebrates. Located in the abdomen behind the stomach, it functions primarily as a gland. Classified as a mixed or heterocrine gland, the pancreas possesses both endocrine and exocrine functions. A significant portion, approximately 99%, is dedicated to its exocrine role, while the remaining 1% serves endocrine functions.

Endocrine and Exocrine Functions

Endocrine Role

As an endocrine gland, the pancreas plays a crucial role in regulating blood sugar levels. It achieves this by secreting hormones such as insulin, glucagon, somatostatin, and pancreatic polypeptide.

Exocrine Role

In its exocrine capacity, the pancreas contributes to the digestive system. It secretes pancreatic juice into the duodenum through the pancreatic duct. This juice is essential for digestion as it contains bicarbonate to neutralize stomach acid, and enzymes to break down carbohydrates, proteins, and fats.

Pancreatic Diseases and Disorders

Pancreatitis

Inflammation of the pancreas, known as pancreatitis, is often caused by chronic alcohol use and gallstones. Pancreatitis represents a significant health concern due to the pancreas’s critical functions.

Diabetes Mellitus

Given its vital role in blood sugar regulation, the pancreas is intrinsically linked to diabetes mellitus, a condition characterized by the improper management of blood sugar levels.

Pancreatic Cancer

Pancreatic cancer, which may develop following chronic pancreatitis or other factors, is particularly dangerous. Its prognosis is often poor because it is usually identified only after metastasizing to other body parts.

Historical and Etymological Notes

The term “pancreas” is derived from the Greek words πᾶν (pân, meaning “all”) and κρέας (kréas, meaning “flesh”). The pancreas’s involvement in diabetes has been recognized since at least 1889, with the discovery of its role in insulin production made in 1921.

Anatomical Divisions

Head of the Pancreas

Location: Nestled within the curvature of the duodenum and encircling the superior mesenteric artery and vein.
Surrounding Structures:
- To the right: Descending part of the duodenum.
- Behind: Inferior vena cava and the common bile duct.
- In front: Peritoneal membrane and the transverse colon.
Uncinate Process: A small extension from the head, located behind the superior mesenteric vein, and sometimes the artery.

Neck of the Pancreas

Function: Connects the head to the body of the pancreas.
Dimensions: Approximately 2 cm (0.79 inches) wide.
Location: In front of the portal vein’s formation site and mostly behind the pylorus of the stomach.
Covering: Surrounded by peritoneum.
Vascular Relation: The anterior superior pancreaticoduodenal artery travels in front of it.

Body of the Pancreas

Size: The largest part of the pancreas.
Positioning: Primarily behind the stomach, tapering along its length.
Surrounding Structures:
- Above: Peritoneum.
- In front: Transverse colon.
- Behind: Aorta, splenic vein, left renal vein, and the start of the superior mesenteric artery.
- Below: Last part of the duodenum, jejunum, and the suspensory ligament of the duodenum.

Tail of the Pancreas

Shape: Narrows towards the end.
Location: Adjacent to the spleen.
Size: Typically 1.3–3.5 cm (0.51–1.38 inches) long.
Positioning: Between the layers of the ligament between the spleen and the left kidney.
Vascular Relation: The splenic artery and vein pass behind it.

Pancreatic Ducts

Main Pancreatic Duct: This duct merges with the common bile duct to form the ampulla of Vater (hepatopancreatic ampulla), encircled by the sphincter of Oddi muscle. It opens into the descending part of the duodenum.
Accessory Pancreatic Duct: A smaller duct, it empties into the duodenum through separate openings located above the main pancreatic duct’s opening.
The regulation of the common bile duct’s entry into the main pancreatic duct is controlled by the sphincter of Boyden.

Arterial Supply of the Pancreas

Overview of Arterial Supply

The arterial blood supply to the pancreas is derived from various major arteries, each contributing to the organ’s complex vascular network.

Primary Arterial Contributions

Common Hepatic Artery: Part of the celiac trunk, it gives rise to other significant arteries that supply the pancreas.
Gastroduodenal Artery: A branch of the common hepatic artery, it plays a crucial role in supplying the pancreas.

Pancreaticoduodenal Arteries

These arteries are vital for supplying blood to the head of the pancreas and the adjacent duodenum.

Anterior Superior Pancreaticoduodenal Artery: Arises from the gastroduodenal artery.
Posterior Superior Pancreaticoduodenal Artery: Also a branch of the gastroduodenal artery.
Anterior Inferior Pancreaticoduodenal Artery: Emanates from the superior mesenteric artery.
Posterior Inferior Pancreaticoduodenal Artery: Another branch of the superior mesenteric artery.

Splenic Artery

Function: As a major branch of the celiac trunk, it primarily supplies the body and tail of the pancreas.

Additional Arterial Contributions

Inferior Pancreatic Artery: This artery contributes to the blood supply of the lower part of the pancreas.
Dorsal Pancreatic Artery: Typically arising from the splenic artery, it also aids in vascularizing the pancreas.

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