Anatomy Of The Pancreas

 

Anatomy of the Pancreas

1. Location

The pancreas is a soft, elongated, retroperitoneal gland with both digestive (exocrine) and hormonal (endocrine) functions. located in the epigastric and left hypochondriac regions.

Lies transversely across the posterior abdominal wall, behind the stomach, between the duodenum (right) and spleen (left).

Vertebral level: L1–L2.

 

• Relations:

Anteriorly: Stomach, transverse colon, transverse mesocolon.

Posteriorly: Inferior vena cava, aorta, left kidney, splenic vein.

Superiorly: Splenic artery.

Inferiorly: Jejunum loops.

2. Parts of the Pancreas

        Pancreas is anatomically divided into four parts

a) Head

Head is the Broadest part, located in the C-shaped curve of the duodenum.

Uncinate process: Posterior projection from the head lying behind the superior mesenteric vessels. Related closely to the bile duct.

b) Neck

Short constricted portion between head and body.

Lies anterior to the formation of the portal vein (from SMV and splenic vein).

c) Body

Elongated part extending to the left across midline.

Lies in front of aorta, left adrenal gland, and left kidney.

Tapers toward the tail.

d) Tail

Narrow left end of the pancreas.

The tail of the pancreas lies anterior to the left kidney, splenorenal ligament, closely related to the splenic hilum and the left colic flexure.

 

 

3. Duct System

Main Pancreatic Duct

Begins in the tail, runs through the length of the pancreas, joins the common bile duct to form the hepatopancreatic ampulla (of Vater).

Opens into the duodenum at the major duodenal papilla.

Controlled by the sphincter of Oddi.

          Accessory Pancreatic Duct

Drains the upper part of the head.

Opens separately into the duodenum at the minor duodenal papilla (about 2 cm above the major papilla).

4. Blood Supply

Arterial Supply

Head & Neck:

Superior pancreaticoduodenal artery (from gastroduodenal artery).

Inferior pancreaticoduodenal artery (from superior mesenteric artery).

Body & Tail:

Branches of splenic artery (e.g., dorsal pancreatic, great pancreatic arteries).

Venous Drainage

Corresponding veins drain into:

Splenic vein.

Superior mesenteric vein.

These ultimately join to form the portal vein.

5. Nerve Supply

Parasympathetic: Vagus nerve → stimulates exocrine & endocrine secretions.

Sympathetic: Thoracic splanchnic nerves (T5–T9) via celiac and superior mesenteric plexuses → regulate blood flow & inhibit secretion.

No direct pain fibers — pain is referred to epigastrium & back.

6. Lymphatic Drainage

Lymph from pancreas drains to:

Pancreaticosplenic nodes (along splenic artery).

Superior mesenteric nodes.

Celiac lymph nodes.

Final drainage into thoracic duct.

7. Histology

Exocrine Component

Acinar cells:

          Pyramid-shaped, arranged in clusters (acini).

          Secrete digestive enzymes: amylase, lipase, proteases (inactive forms).

Ductal cells:

         Secrete bicarbonate-rich fluid to neutralize gastric acid.

Endocrine Component

Islets of Langerhans (1–2% of pancreatic tissue):

Alpha cells → glucagon (↑ blood glucose).

Beta cells → insulin (↓ blood glucose).

Delta cells → somatostatin (inhibits hormone secretion).

PP cells → pancreatic polypeptide (regulates pancreatic secretion).

Epsilon cells → ghrelin (appetite regulation).

8. Functions

Exocrine Functions

Production of digestive enzymes:

Carbohydrate digestion: Amylase.

Protein digestion: Trypsin, chymotrypsin, carboxypeptidases.

Fat digestion: Lipase, phospholipase, cholesterol esterase.

                   Secretion of bicarbonate to neutralize acidic chyme.

Endocrine Functions

Regulation of blood glucose & metabolism via hormones:

         Insulin, glucagon, somatostatin, pancreatic polypeptide.