Anatomy of the Liver – Study Notes

Overview:

• The liver (Hepar in Latin) is the largest internal organ of the human body.

• Weight: ~1.5 kg.

• Location: Lies primarily on the right side of the abdominal cavity, protected by the ribs.

• Main Function: Filters blood coming from the digestive tract before it passes to the rest of the body.

Functions of the Liver

1. Filtration and Detoxification

   • Filters blood from the digestive organs via the portal venous system.

   • Removes toxins, drugs, and harmful substances.

   • Detoxifies alcohol and metabolizes medications.

2. Metabolism and Synthesis

   • Produces cholesterol for hormone and vitamin D synthesis.

   • Synthesizes bile, important for fat digestion.

   • Produces plasma proteins like albumin and clotting factors.

3. Storage

   • Stores glycogen (for glucose regulation), fat-soluble vitamins (A, D, E, K), and iron.

   • Converts glycogen to glucose during hypoglycemia.

4. Immune and Endocrine Role

   • Contains Kupffer cells that remove pathogens and debris from blood.

   • Plays a role in hormone metabolism.

Portal System

• The portal venous system drains nutrient-rich blood from the stomach, intestines, spleen, and pancreas into the portal vein.

• The portal vein → liver → filters blood → exits via the hepatic veins → inferior vena cava (IVC) → systemic circulation.

• Purpose: To process nutrients and detoxify substances before systemic distribution.

Topography (Position and Relations)

Holotopy (Position in the Body)

• Occupies the upper right quadrant of the abdominal cavity.

• Extends across:

  • Right hypochondriac region

  • Epigastric region

  • Left hypochondriac region

Skeletopy (Relation to Bones)

• Superior Border:

  • Starts at the 10th rib (right side) → up to 4th intercostal space (midclavicular line) → 5th intercostal space (left of sternum) → ends at 6th intercostal space.

• Inferior Border:

  • Starts at 10th rib (right) → across 8th–9th ribs → ends at 6th intercostal space (left).

• Posteriorly: Between T9–T11 vertebrae.

Syntopy (Relation to Organs)

• Superior Surface (Diaphragmatic surface): Lies directly beneath the diaphragm.

• Inferior Surface (Visceral surface): Faces other organs:

  • Stomach (pylorus and fundus)

  • Duodenum (upper part)

  • Colon

  • Right kidney

  • Esophagus

External Structure

Anterior View

• Prominent falciform ligament divides right and left lobes.

• Inferior margin: Sharp and projects downward.

Posterior View

• Rounded posterior margin (less sharp).

• Contains the bare area (area nuda) — the only region not covered by peritoneum, directly contacting the diaphragm.

Grooves and Lobes

• Right sagittal groove:

  • Formed by the fossa for gallbladder (anteriorly) and fossa for IVC (posteriorly).

  • Separates the right lobe from other lobes.

• Left sagittal groove:

  • Formed by:

    • Ligamentum teres hepatis (round ligament) – inferiorly.

    • Ligamentum venosum (venous ligament) – superiorly.

  • Separates left lobe from the others.

• Transverse groove (Porta Hepatis):

  • Horizontal depression through which vessels and ducts enter or leave the liver.

  • Divides caudate lobe (superior) and quadrate lobe (inferior).

Lobes

• Anterior side: Right and left lobes.

• Posterior side: Right, left, caudate, and quadrate lobes (4 total).

Functional Segmentation (Couinaud System)

• Divides liver into 8 functionally independent segments.

• Each segment has its own:

  • Vascular inflow

  • Vascular outflow

  • Biliary drainage

• Important for surgical resections.

Porta Hepatis (Hilum of Liver)

Structures entering/leaving:

• Common hepatic duct

• Hepatic portal vein

• Proper hepatic artery

• Hepatic lymph nodes

• Hepatic plexus (nerves)

• Covered by hepatoduodenal ligament, connecting liver → duodenum.

Coverings of the Liver

1. Tunica fibrosa (fibrous capsule) – protective connective tissue sheath.

2. Visceral peritoneum (Tunica serosa) – serous membrane that reduces friction.

   • Exception: Bare area, which directly contacts the diaphragm.

Ligaments of the Liver

A. Ligaments Connecting Liver to the Diaphragm

1. Falciform ligament – attaches liver to anterior abdominal wall.

2. Coronary ligament – connects liver to diaphragm; surrounds bare area.

3. Right triangular ligament – right lateral edge.

4. Left triangular ligament – left lateral edge.

B. Ligaments Connecting Liver to Other Organs

(All originate from the Porta Hepatis)

1. Hepatogastric ligament – liver → stomach.

2. Hepatoduodenal ligament – liver → duodenum (contains bile duct, vessels, nerves).

3. Hepatorenal ligament – liver → right kidney (sometimes considered part of coronary ligament).

4. Round ligament (Ligamentum teres hepatis) – remnant of left umbilical vein, runs to umbilicus.

Key Clinical Notes

• Bare Area: Site where infections can spread between thorax and abdomen.

• Porta Hepatis: Critical for hepatic surgeries and liver transplantation.

• Couinaud Segmentation: Guides segmental resections to preserve function.

Summary

Feature	Description
Weight	~1.5 kg
Location	Right upper abdomen under ribs
Surfaces	Diaphragmatic (superior) & Visceral (inferior)
Functions	Filtration, metabolism, storage, bile production
Major Ligament	Falciform (divides right & left lobes)
Bare Area	Posterior surface, not covered by peritoneum
Porta Hepatis	Entry/exit for ducts, vessels, and nerves
Segments	8 functionally independent (Couinaud)