Anatomy and Physiology of the Pancreas

Anatomical Position and Relations

• Location: Transpyloric plane, in the epigastric and left hypochondrium regions
• Head: Found within C-shaped duodenum
  • Duodenum Parts:
    • D1 (Superior/ Bulbar Duodenum)
    • D2 (Descending Duodenum)
    • D3 (Inferior Horizontal Duodenum)
    • D4 (Ascending Duodenum)
• Tail: Close contact with the spleen
• Posterior to Stomach: Separated by the lesser sac

Embryology

• Lesser Sac (Omental Bursa): Formed during stomach rotation and liver growth
• Abdominal Cavity: Initially split into right and left sac
  • Right Sac: Becomes lesser sac (smaller, dark blue)
  • Left Sac: Becomes greater sac (larger, light blue)
• Foramen of Winslow: Connects both sacs via a small opening
• Pancreas: Develops behind peritoneum, behind right sac and stomach

Anatomical Segments

• Head: Lies within C-shaped duodenum
• Uncinate Process: Inferior to head, posterior to superior mesenteric vessels
• Neck: Overlies superior mesenteric vessels (groove on posterior aspect)
• Body: Behind stomach, left of superior mesenteric vessels
• Tail: Close to spleen hilum, within splenorenal ligament
  • Peritoneal Relation:
    • Tail: Intraperitoneal
    • Head, Uncinate Process, Neck, Body: Retroperitoneal

Blood Supply

• Major Supplier: Coeliac trunk
• Neck, Body, Tail: Supplied by pancreatic branches of splenic artery
• Head and Uncinate Process: Supplied by superior and inferior pancreaticoduodenal arteries
  • Superior Pancreaticoduodenal Artery: Branch of gastroduodenal artery (common hepatic artery → celiac trunk)
  • Inferior Pancreaticoduodenal Artery: Branch of superior mesenteric artery

Physiology

Exocrine Pancreas

• Acinar Cells: Produce digestive enzymes (trypsinogen, amylase, lipase)
  • Secreted in inactive form, activated in the duodenum

Endocrine Pancreas

• Islet Cells: Make up 1-2% of pancreatic tissue
• Hormones: Insulin and glucagon
  • Islet of Langerhans: Groups of endocrine cells
    • Beta Cells: Produce insulin (decreases glucose levels)
    • Alpha Cells: Release glucagon (increases glucose levels)
    • Delta Cells: Secrete somatostatin