Blood Supply and Nerve Supply of the Liver

Blood Supply

Arterial Supply (25% of blood flow)

• Right hepatic artery - supplies the right lobe (larger branch)
• Left hepatic artery - supplies the left lobe

• The right hepatic artery may arise from the superior mesenteric artery (runs posterior to the bile duct, behind the pancreatic head) - this is the most common significant variant
• The left lobe artery may be augmented or replaced by a branch of the left gastric artery running in the lesser omentum

Portal Venous Supply (75-80% of blood flow)

• Nutrients and toxic materials absorbed from the intestine
• Blood cell breakdown products from the spleen
• Endocrine secretions (insulin, glucagon) from the pancreas and GI enteroendocrine cells

Because blood from both sources mixes just before perfusing hepatocytes, liver cells are never exposed to fully oxygenated blood. - Histology: A Text and Atlas (Eroschenko)

Intrahepatic Microcirculation

Portal triad: terminal hepatic artery, portal vein, and bile duct. Blood flows through sinusoids toward the central vein (terminal hepatic venule), while bile flows in the opposite direction. (Histology: A Text and Atlas)

Venous Drainage

Nerve Supply

Sympathetic Supply

• Preganglionic fibers: T5-T10 spinal cord segments
• Route: Via the greater splanchnic nerve → celiac ganglia (synapse) → post-ganglionic fibers via the hepatic plexus
• Hepatic plexus is a continuation/extension of the celiac plexus, the largest autonomic plexus in the abdomen
• Sympathetic fibers primarily supply the hepatic arteries (causing vasoconstriction) and travel along the vessel walls into the liver parenchyma
• Afferent sympathetic fibers carry visceral pain signals from the liver and biliary tract (T5-T10 via celiac plexus)

Parasympathetic Supply

• Source: The vagus nerve (CN X) - both left and right vagal trunks
• Vagal fibers travel via the hepatic branches of the anterior and posterior vagal trunks to the hepatic plexus
• Parasympathetic fibers innervate the gallbladder, extrahepatic bile ducts, and the liver parenchyma
• Afferent parasympathetic fibers carry sensations via the vagus nerve

Hepatic Plexus

Clinical Relevance - Referred Pain

• Acute distension of the liver capsule (e.g., hepatitis, congestive hepatopathy, rapidly enlarging abscess) causes right upper quadrant pain referred to the right shoulder, via phrenic nerve innervation of the diaphragmatic peritoneum overlying the liver - Sabiston Textbook of Surgery
• The hepatic arteries receive sympathetic fibers; the gallbladder and extrahepatic bile ducts receive both sympathetic and parasympathetic fibers
• The clinical significance of hepatic autonomic nerves is not fully understood, but they modulate glucose metabolism and portal blood flow

• Bailey and Love's Short Practice of Surgery, 28th Ed. - Ch. 69: Blood supply and hilum of the liver
• Sabiston Textbook of Surgery - Ch. 89: Functional anatomy and innervation
• Histology: A Text and Atlas (Eroschenko) - Ch. 18: Blood supply to the liver
• Color Atlas of Human Anatomy, Vol. 2 - Vessels, nerves, and lymphatic drainage
• Miller's Anesthesia, 10th Ed. - Table 14.1: Visceral innervation of abdominal organs

Lymphatic Drainage of the Liver

Origin of Hepatic Lymph

The Glisson capsule lymphatic plexus communicates with intrahepatic lymphatics through anastomotic channels. In conditions of impaired venous drainage (e.g., venous outflow obstruction or cirrhosis), lymphatic drainage becomes prominent through the Glisson capsule. - Yamada's Textbook of Gastroenterology, 7th ed.

Superficial Lymphatics

Deep Lymphatics

1. With the portal vein - course with portal vein and its tributaries to the hilum, then drain into the hepatic nodes at the porta hepatis
2. With the hepatic veins - follow the hepatic veins converging on the IVC, pass through the diaphragmatic hiatus, and drain into the posterior mediastinal lymph nodes

Efferent Pathway (Summary)

Space of Disse
       ↓
Portal tract lymphatics
       ↓
Hepatic nodes (porta hepatis / hepatoduodenal ligament)
       ↓
Celiac lymph nodes (along the hepatic artery)
       ↓
Cisterna chyli → Thoracic duct

Hepatic veins → posterior mediastinal nodes → thoracic duct

Anterior surface → parasternal nodes
Posterior left lobe → left gastric nodes

Key Lymph Node Groups

• Hepatic nodes - lie along the porta hepatis and hepatic vessels in the lesser omentum; the primary first-echelon nodes. Their efferents drain to the celiac nodes.
• Celiac nodes - receive efferents from the hepatic nodes; drain into the cisterna chyli
• Phrenic nodes - receive drainage from the posterior bare area
• Posterior mediastinal nodes - receive drainage via the hepatic veins/IVC route through the diaphragm
• Parasternal nodes - receive drainage from the anterior surface via the falciform ligament

Clinical Significance

• Portal hypertension / cirrhosis: Impaired sinusoidal flow increases lymph production dramatically; the Glisson's capsule pathway becomes a dominant overflow route, contributing to ascites formation when lymphatic capacity is overwhelmed
• Hepatocellular carcinoma / cholangiocarcinoma: Spread follows these lymphatic routes - hepatic nodes → celiac nodes; also to posterior mediastinal nodes and parasternal nodes in advanced disease
• Liver congestion (e.g., right heart failure): Increased hepatic lymph production contributes to chylous effusions and ascites

• Fischer's Mastery of Surgery, 8th ed. - Ch. 173: Lymphatic Drainage (Fig. 173.10)
• Yamada's Textbook of Gastroenterology, 7th ed. - Vascular and lymphatic network
• Sabiston Textbook of Surgery - Ch. 89: Functional anatomy, lymphatics
• Color Atlas of Human Anatomy, Vol. 2 - Regional lymph nodes of the liver

Fig. 173.11 - Innervation of the liver: the hepatic plexus (purple) receives input from the celiac ganglion/sympathetic trunk (yellow) and both anterior and posterior vagal trunks (green). (Fischer's Mastery of Surgery, 8th ed.)