Pancreas - Structure, Islets of Langerhans, and Syntopy

Pancreas - Structure, Islets of Langerhans, and Syntopy

The pancreas is a vital retroperitoneal organ located in the upper abdominal cavity. It has both exocrine and endocrine functions, essential for digestion and metabolic regulation. Below is a detailed explanation based on Gray’s Anatomy and Sobotta Atlas of Human Anatomy.

1.     Structure of the Pancreas

The pancreas is an elongated, lobulated gland divided into four main parts:

·      Head: Lies in the C-shaped curve of the duodenum and is connected to it by the pancreaticoduodenal arteries.

·      Uncinate Process: A projection of the head that extends posteriorly, wrapping around the superior mesenteric vessels.

·      Neck: A constricted region connecting the head and the body, lying anterior to the superior mesenteric vein and portal vein.

·      Body: The largest part of the pancreas, extending transversely across the posterior abdominal wall.

·      Tail: The narrowest portion, located anterior to the left kidney and extending into the splenorenal ligament, where it contacts the hilum of the spleen.

The pancreas is primarily composed of lobules of glandular tissue supported by connective tissue septa, containing acini (exocrine units) and Islets of Langerhans (endocrine units).

2.     Islets of Langerhans

The Islets of Langerhans are scattered clusters of endocrine cells within the pancreatic parenchyma.

·      Histological Features:

o   Comprised of multiple cell types, each secreting distinct hormones:

§  Alpha (α) cells: Secrete glucagon (15-20% of cells).

§  Beta (β) cells: Secrete insulin (60-70% of cells).

§  Delta (δ) cells: Secrete somatostatin (5-10% of cells).

§  PP cells: Secrete pancreatic polypeptide (rare).

§  Highly vascularized, allowing rapid release of hormones into the bloodstream.

·      Function: Regulates blood glucose homeostasis and systemic metabolism.

·      Clinical Correlation: Dysfunction of β-cells is a key feature of diabetes mellitus.

3.     Syntopy of the Pancreas

The pancreas is surrounded by several important anatomical structures:

·      Anterior Relations:

o   Stomach (separated by the lesser sac).

o   Transverse colon and its mesocolon.

·       Posterior Relations:

o   Abdominal aorta, inferior vena cava, left renal vein, and splenic vein.

o   Vertebral column (T12-L2 vertebral level).

·       Superior Relations:

o   Celiac trunk and splenic artery.

·       Inferior Relations:

o   Superior mesenteric artery and vein.

·       Lateral Relations:

o   Tail contacts the spleen laterally.

o   Head surrounds the duodenum medially.

Clinical Relevance

·       Pancreatic Duct System:

o   The main pancreatic duct (duct of Wirsung) joins the common bile duct to form the hepatopancreatic ampulla (ampulla of Vater), opening into the duodenum at the major duodenal papilla.

o   The accessory pancreatic duct (duct of Santorini) may also drain the pancreas.

·       Diseases:

o   Pancreatitis, pancreatic cancer, and diabetes mellitus are common clinical issues associated with the pancreas.

·       Surgical Considerations:

o   The pancreas’s close relationship to major vessels and retroperitoneal position complicates surgical interventions.

The answer and the images are based on:

·      Gray’s Anatomy (41st Edition)

·      Sobotta Atlas of Human Anatomy (16th Edition, Volumes 1 & 2)