Liver

Liver Anatomy

General Overview

  • Segmental Organ: The liver is the largest and one of the most complex organs in the body, located inferior to the diaphragm.

  • Metabolic Functions: A single liver cell can conduct over 500 separate metabolic activities.

  • Weight Variation:

    • Birth: Weighs about 150 g.

    • Adult Male: Ranges from 1.4 kg to 1.8 kg.

    • Adult Female: Ranges from 1.2 kg to 1.4 kg.

  • Sonographic Evaluation: The liver is quite accessible for ultrasound evaluations.

Location and Shape

  • Occupies Regions:

    • Almost all of the right hypochondrium.

    • Greater part of the epigastrium.

    • Part of the left hypochondrium.

  • Contour Variation: The contour and shape of the liver can vary according to the individual's habitus.

Relations

Anterior Relations

  • Diaphragm

  • Right and left costal margins.

  • Right and left pleura.

  • Lower margins of both lungs.

  • Xiphoid process.

  • Anterior abdominal wall.

Posterior Relations

  • Diaphragm.

  • Right kidney.

  • Hepatic flexure of the colon.

  • Duodenum.

  • Gallbladder.

  • Inferior vena cava.

  • Esophagus.

  • Fundus of the stomach.

Hepatic Recesses

  • Clinical Importance: Spaces between the liver and surrounding structures where infected fluids may accumulate.

    1. Subphrenic Spaces: Spaces located between the diaphragm and liver.

    2. Subhepatic Space: Space between the inferior surface of the liver and stomach.

    3. Morison's Pouch: Space posterior to the right liver lobe and anterior to the right kidney.

Liver Anatomy - Ligaments

  • Glisson’s Capsule: Composed of two layers: an outer serous layer and an inner fibroelastic connective tissue layer. It reflects sound beams, appearing hyperechoic.

  • Bare Area: The region of the liver resting directly on the diaphragm, with specific fossae (IVC fossae, Porta Hepatis, Gallbladder fossae).

  • Connecting Ligaments:

    • Falciform Ligament: Attaches liver to anterior abdominal wall.

    • Ligamentum Teres: Remnant of the umbilical vein, found within the falciform ligament.

    • Coronary Ligaments: Connect the liver's superior surface to the diaphragm.

    • Ligamentum Venosum: Fibrous remnant of the ductus venosus.

Lobes of the Liver

  • Right Lobe: The largest lobe, exceeding the left 6:1 ratio, occupying the right hypochondrium.

  • Left Lobe: Always smaller; size and shape can vary.

  • Caudate Lobe: Located postero-superiorly, bordered by important anatomical structures (Porta Hepatis, IVC fossa).

  • Quadrate Lobe: Postero-inferior to the left lobe, positioning between the gallbladder and the ligamentum teres.

  • Riedel's Lobe: An anatomical variant characterized by a tongue-like projection of the right lobe.

Fissures of the Liver

  • Main Lobar Fissure: Separates right and left lobes, housing the main hepatic vein.

  • Intersegmental Fissures: Include right intersegmental and left intersegmental fissures, affecting lobar divisions.

Blood Supply and Drainage

  • Dual Blood Supply:

    • Hepatic Artery: Supplies arterial blood (20%).

    • Portal Vein: Main blood supply (80%), bringing in less oxygenated blood carrying nutrients from the intestine.

  • Venous Drainage: Through three hepatic veins draining into the inferior vena cava (IVC).

    • Middle Hepatic Vein: Divides right and left lobes.

    • Right and Left Hepatic Veins: Further divides the respective lobes into segments.

Liver Functions

  • Metabolic Activities:

    • Secretes bile, removes nutrients from blood, converts glucose to glycogen, stores vitamins, iron.

    • Metabolizes proteins, fats, carbohydrates; manufactures plasma proteins.

    • Detoxifies drugs and poisons; phagocytizes bacteria and weakened RBCs.

Ultrasound Evaluation

  • Indications: Abdominal discomfort, abnormal LFTs, jaundice, hepatomegaly, and following cancer for liver metastasis.

Patient Preparation

  • NPO for 6-8 hours, avoid smoking, and be cautious in diabetic patients.

Scanning Techniques

  • Sagittal and Transverse Scans: Evaluate the liver systematically in both dimensions and as necessary.

  • Observe liver echogenicity relative to adjacent structures for diagnosis.