Pancreas and Spleen

Pancreas Anatomy - Gut's Sweetbread Secret

• Location: Mostly retroperitoneal (tail is intraperitoneal); L1-L2 level, posterior to stomach.
• Parts (Right to Left):
  • Head: In C-loop of duodenum. Uncinate process posterior to SMV/SMA. Common Bile Duct (CBD) passes through/posterior.
  • Neck: Overlies Superior Mesenteric Vein (SMV), Superior Mesenteric Artery (SMA), portal vein origin.
  • Body: Crosses aorta, left kidney; posterior to omental bursa.
  • Tail: Reaches splenic hilum (within splenorenal ligament).
• Ducts: Main pancreatic duct (Wirsung) joins CBD at ampulla of Vater. Accessory duct (Santorini) variable.

, main and accessory pancreatic ducts, and key relations like duodenum, superior mesenteric vessels (SMV, SMA), portal vein, splenic vein, and common bile duct)

• Key Relations:
  • Posterior: IVC, aorta, portal vein, splenic vein, bile duct, left kidney.
  • Anterior: Stomach, transverse mesocolon.
• Arterial Supply:
  • Head/Uncinate: Superior & Inferior pancreaticoduodenal arteries (from celiac trunk & SMA branches).
  • Body/Tail: Splenic artery branches.
• Venous Drainage: Via pancreatic veins to splenic vein, SMV, then portal vein.

⭐ Cancer of the head of pancreas commonly causes painless obstructive jaundice due to CBD compression.

Pancreas Histo & Embryo - Islet Islands & Budding Beginnings

Exocrine Pancreas: Acini (serous, zymogen granules), centroacinar cells. Ducts: intercalated → intralobular → interlobular → main.

Endocrine Pancreas (Islets of Langerhans): 📌 Mnemonic (B-I-G A-G-S): Beta cells (Insulin - central, Greatest); Alpha cells (Glucagon); Delta cells (Somatostatin).

Embryology (Foregut Origin):

• Dorsal bud → body, tail, superior head, accessory duct.
• Ventral bud → inferior head, uncinate, main duct.
• Rotation & fusion: Ventral bud rotates dorsally, fuses with dorsal; ducts fuse.

Congenital Anomalies:

• Annular pancreas: duodenal obstruction.
• Pancreas divisum: duct fusion failure.
• Ectopic pancreas: atypical sites.

⭐ Pancreas divisum: failed dorsal/ventral duct fusion. Most common anomaly (~10%), risks pancreatitis.

Spleen Anatomy & Relations - Body's Blood Bank

• Location: LUQ, intraperitoneal. Lies under left ribs 9-11, axis along 10th rib.
• Normal Size/Weight: 📌 1x3x5 inches (thick x broad x long), 7oz (~200g).
• Surfaces & Impressions:
  • Diaphragmatic: Convex, smooth; faces diaphragm.
  • Visceral: Concave; gastric, renal (L. kidney), colic (splenic flexure), pancreatic (tail) impressions.
• Borders: Superior (notched), inferior, anterior (sharp), posterior.
• Hilum: Medial aspect; entry/exit for splenic artery/vein, nerves.
• Key Ligaments:

  Ligament	Contents
  Gastrosplenic	Short gastric, L. gastroepiploic vessels
  Splenorenal	Splenic vessels, Pancreas tail
  Phrenicocolic	Supports spleen inferiorly

• Arterial Supply: Splenic artery (from celiac trunk) to hilum.
• Venous Drainage: Splenic vein joins SMV to form Portal Vein.

⭐ Tail of pancreas in splenorenal ligament: risk during splenectomy.

Spleen Histo & Functions - Red & White Sentinel

Histology: Fibroelastic capsule (smooth muscle), trabeculae.

• Blood via central arteries (white pulp).
• Open theory: Arterioles to red pulp cords → sinusoids.
• Closed theory: Arterioles direct to sinusoids. (Both occur).

Key Functions:

• Immune: Activates lymphocytes, antibody production.
• Filtration: Removes old RBCs/platelets, microbes.
• Hematopoiesis: (Fetal).
• Storage: RBCs, platelets.

⭐ Post-splenectomy: ↑ risk of overwhelming sepsis from encapsulated bacteria (e.g., Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis) due to loss of splenic phagocytic and immune functions.

High‑Yield Points - ⚡ Biggest Takeaways

• Pancreas: mostly retroperitoneal; tail is intraperitoneal in splenorenal ligament.
• Head of pancreas in duodenal C-loop; uncinate process posterior to SMV/SMA.
• Main pancreatic duct (Wirsung) joins CBD forming ampulla of Vater.
• Spleen: intraperitoneal, related to left ribs 9-11.
• Splenic artery (celiac trunk); splenic vein joins SMV forming portal vein.
• Gastrosplenic ligament: short gastric vessels; Splenorenal ligament: splenic vessels, pancreatic tail.
• Accessory spleens (splenunculi) are common, often near splenic hilum or tail of pancreas.