Overview
This lecture covers the anatomy, blood supply, histology, development, and clinical significance of the pancreas, emphasizing its structure, functions, and related disorders.
Anatomical Features of the Pancreas
- The pancreas is an elongated gland located in the epigastric, umbilical, and left hypochondriac regions at L1 and L2 vertebrae.
- It functions as both an exocrine (digestive enzyme secretion) and endocrine gland (hormone secretion).
- The pancreas is J-shaped with four parts: head, neck, body, and tail.
- Typical measurements: 12-15 cm length, 3-4 cm width, 1.5-2 cm thickness, 80-90 grams weight.
Head
- Lies in the C-shaped curve of the duodenum at L2; has three borders and two surfaces.
- The uncinate process projects from the head, related to superior mesenteric vessels and abdominal aorta.
Neck
- Constricted area between head and body, 2.5 cm long, directed upwards and left.
- Related anteriorly to pylorus, posteriorly to the formation of the portal vein.
Body
- Elongated, left of neck to tail, triangular in cross-section.
- Has three borders and three surfaces, related to key arteries, veins, and organs (stomach, spleen, kidney).
Tail
- Narrow left end within the lienorenal ligament, adjacent to spleen, rich in islets of Langerhans.
Duct System
- Main pancreatic duct (duct of Wirsung): transports digestive enzymes, joins bile duct to open at major duodenal papilla.
- Accessory pancreatic duct: opens at minor duodenal papilla; may not always communicate with the main duct.
Blood Supply and Drainage
- Arterial supply: splenic artery (main), superior and inferior pancreaticoduodenal arteries.
- Venous drainage: portal vein, superior mesenteric vein, splenic vein.
- Lymphatic drainage: pancreaticosplenic and pyloric lymph nodes, draining to celiac and superior mesenteric nodes.
Nerve Supply
- Sympathetic: splanchnic nerves (vasomotor function).
- Parasympathetic: vagus nerve (stimulates pancreatic secretion).
- Cholecystokinin hormone from duodenum also influences secretion.
Histology
- Exocrine part: acinar cells produce digestive enzymes (trypsin, amylase, lipase).
- Endocrine part: islets of Langerhans contain beta (insulin), alpha (glucagon), and delta (somatostatin) cells.
Development
- Formed from dorsal and ventral pancreatic buds; dorsal forms most of gland, ventral forms uncinate process and part of head.
- Ducts of both buds combine to form the main and accessory ducts.
Clinical Anatomy
- Pancreatitis: inflammation due to gallstones or alcohol; symptoms include epigastric pain, nausea, vomiting, jaundice.
- Diabetes mellitus: hyperglycemia from insulin deficiency (type 1) or resistance (type 2); symptoms include polyuria, polydipsia, weight loss.
- Annular pancreas: developmental anomaly where pancreas encircles duodenum.
- Accessory pancreatic tissue: ectopic pancreatic cells, most commonly found in the duodenum.
Key Terms & Definitions
- Exocrine gland — organ that secretes substances into ducts (e.g., pancreatic enzymes).
- Endocrine gland — organ that releases hormones directly into the blood.
- Islets of Langerhans — clusters of pancreatic endocrine cells secreting insulin, glucagon, and somatostatin.
- Main pancreatic duct (duct of Wirsung) — chief duct draining pancreatic enzymes into the duodenum.
- Accessory pancreatic duct — secondary duct draining pancreatic juice.
- Annular pancreas — abnormal ring of pancreatic tissue encircling the duodenum.
- Pancreatitis — inflammation of the pancreas.
Action Items / Next Steps
- Review anatomical diagrams of the pancreas.
- Study the blood supply and drainage routes.
- Prepare for a quiz on pancreatic histology and clinical correlations.