Liver, Gallbladder and Biliary Tract

Liver Anatomy - The Body's Powerhouse

Largest gland (~1.5 kg); RUQ, under diaphragm.

• Lobes & Segments:
  • Anatomical: Right, Left, Caudate, Quadrate.
  • Functional: 8 Couinaud segments (key for resections); Cantlie's line divides.
• Coverings: Glisson's capsule; Peritoneum (except bare area).
• Ligaments: Falciform, Coronary, Triangular, Lig. teres hepatis (obliterated umbilical vein), Lig. venosum.
• Blood Supply (Dual):
  • Portal Vein: ~75% inflow (nutrient-rich).
  • Hepatic Artery: ~25% inflow (oxygenated).
  • Drainage: Hepatic veins → IVC.
• Porta Hepatis: Gateway for portal triad (hepatic artery, portal vein, bile duct). 📌 Mnemonic: "PAD"

⭐ Cantlie's line, from IVC fossa to gallbladder fossa, marks the true functional division of the liver.

Liver Microanatomy - Tiny Titans at Work

• Hepatic Lobule: Hexagonal; central vein, portal triads at periphery.
• Portal Triad: Portal vein, hepatic artery, bile duct. (📌 PAB)
• Hepatocytes: In cords; metabolic, synthetic, detox functions.
• Sinusoids: Channels with fenestrated endothelium, Kupffer cells (macrophages).
• Space of Disse: Perisinusoidal; exchange site; Stellate (Ito) cells (Vit A, fibrosis).
• Acinus (Functional):
  • Zone 1 (Periportal): ↑O₂, viral hepatitis, gluconeogenesis.
  • Zone 3 (Centrilobular): ↓O₂, ischemia, alcohol, P450.

⭐ Zone 3 is most susceptible to ischemic injury and toxic damage due to its poor oxygenation and high concentration of P450 enzymes.

Gallbladder - Bile's Little Buddy

• Location: Fossa on visceral surface of liver, between quadrate lobe & right lobe.
• Function: Stores & concentrates bile (capacity 30-50 mL).
• Parts: Fundus, body, infundibulum (Hartmann's pouch - common site for gallstones), neck.
• Blood Supply: Cystic artery (usually from right hepatic artery in Calot's triangle).
• Venous Drainage: Cystic vein → portal vein.
• Innervation: Vagus (parasympathetic), celiac plexus (sympathetic).

⭐ Calot's Triangle Boundaries: Cystic duct (inferiorly), common hepatic duct (medially), and inferior surface of the liver (superiorly). Contents: Cystic artery, cystic lymph node (of Lund).

Biliary Tract - The Bile Superhighway

• Bile Flow: Intrahepatic ducts → R/L Hepatic Ducts → Common Hepatic Duct (CHD).
  • CHD joins Cystic Duct (from Gallbladder) → forms Common Bile Duct (CBD).
  • CBD joins Main Pancreatic Duct → Hepatopancreatic Ampulla of Vater → empties into Duodenum via Sphincter of Oddi.
• Gallbladder: Concentrates & stores bile (capacity 30-50 mL). Cholecystokinin (CCK) triggers release.
• CBD: Normal diameter ≤ 6 mm (may ↑ to 10 mm post-cholecystectomy or with age).

⭐ > Courvoisier's Law: A palpable, non-tender gallbladder with jaundice often indicates periampullary malignancy, not gallstones.

Hepato-Biliary Clinicals - Surgeon's Eye View

• Jaundice: Differentiate obstructive (surgical) vs. hepatocellular.
• Gallbladder & Biliary Tree:
  • Cholecystitis: Murphy’s sign, RUQ pain.
  • Cholelithiasis: RUQ pain, fat intolerance.
  • Cholangitis: Charcot’s triad (fever, pain, jaundice); Reynold’s pentad (+ shock, AMS).
  • Calot’s Triangle: For cholecystectomy. Boundaries: Cystic Duct, Common Hepatic Duct, Inf. Liver Edge. 📌 Cystic Artery within.
• Liver:
  • Portal Hypertension: Varices, ascites.
  • Trauma: Pringle maneuver (↓bleed).
  • Resection: Couinaud segments guide.

⭐ Jaundice + palpable, non-tender gallbladder = likely malignancy, not stones (Courvoisier's Law).

High‑Yield Points - ⚡ Biggest Takeaways

• Cantlie's line demarcates true right/left functional liver lobes.
• Portal triad (portal vein, hepatic artery, bile duct) is in the hepatoduodenal ligament.
• The bare area of the liver lacks peritoneal covering, allowing direct contact with the diaphragm.
• Calot's triangle (cystic duct, common hepatic duct, liver edge) contains the cystic artery.
• Sphincter of Oddi regulates bile and pancreatic juice flow into the duodenum.
• Couinaud segments (I-VIII) form the basis for hepatic surgical resections.
• Hartmann's pouch of the gallbladder is a common site for gallstone impaction.