Liver

Liver Anatomy Overview

  • Segmental Organ

    • Lies inferior to the diaphragm.

    • Considered the largest and one of the most complex organs in the body.

    • A single liver cell can perform over 500 separate metabolic activities.

Size and Variation

  • Weight:

    • Weighs about 150 g at birth.

    • Adult male weight ranges from 1.4 kg to 1.8 kg.

    • Adult female weight ranges from 1.2 kg to 1.4 kg.

  • Shape:

    • The liver's contour and shape vary according to the patient’s habitus.

    • Sonographic accessibility: Highly accessible for evaluation using ultrasound.

Anatomical Location

  • Occupies:

    • Almost all of the right hypochondrium.

    • Greater part of the epigastrium.

    • Part of the left hypochondrium.

Anterior Relations of the Liver

  • Relations include:

    • Diaphragm

    • Right and left costal margins

    • Right and left pleura

    • Lower margins of both lungs

    • Xiphoid process

    • Anterior abdominal wall

Posterior Relations of the Liver

  • Relations include:

    • Diaphragm

    • Right kidney

    • Hepatic flexure of the colon

    • Duodenum

    • Gallbladder

    • Inferior vena cava

    • Esophagus

    • Fundus of stomach

Hepatic Recesses

  • Spaces between the liver and surrounding structures, important for clinical evaluation, especially for abscess formation:

    1. Subphrenic spaces (left and right): Between diaphragm and liver, adjacent to the falciform ligament.

    2. Subhepatic space: Between inferior surface of the liver and stomach.

    3. Morison's pouch: Posterior to the right liver lobe and anterior to the right kidney.

Glisson’s Capsule

  • Composed of two layers:

    • Outer serous layer: Derived from visceral peritoneum.

    • Inner dense, fibroelastic connective tissue layer: Known as Glisson capsule, appears hyperechoic on ultrasound due to its density.

Bare Area of the Liver

  • The area that rests directly on the diaphragm.

  • Exceptions to peritoneum coverage include:

    • IVC fossae

    • Porta Hepatis

    • Gallbladder fossae

Ligaments of the Liver

  • Attaches to the diaphragm and abdominal walls:

    • Falciform ligament: Attaches the anterior surface of the liver to the abdominal wall, contains remnant ligamentum teres.

    • Ligamentum teres: Remnant of umbilical vein, may recanalize in portal hypertension.

    • Coronary ligament (right and left): Attaches superior surface to diaphragm.

    • Ligamentum venosum: Fibrous remnant of ductus venosus, separates left lobe from caudate lobe.

Liver Lobes

  • Right Lobe: Largest, exceeds left lobe by a ratio of 6:1, bordered by falciform ligament and marked by IVC, porta hepatis, and gallbladder fossae.

  • Left Lobe: Smaller and varies in size and shape compared to the right lobe.

  • Caudate Lobe: Small lobe on postero-superior surface, bounded by porta hepatis, fossa for IVC, and fossa for ductus venosus.

  • Quadrate Lobe: Small, lies between gallbladder and ligamentum teres fissure.

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

Liver Fissures

  • Main lobar fissure: Separates the right and left lobes of the liver.

  • Right intersegmental fissure: Divides the right lobe into anterior and posterior segments.

  • Left intersegmental fissure: Divides the left lobe into medial and lateral segments.

Blood Supply of the Liver

  • Hepatic artery: Supplies 20% of blood; derived from celiac trunk.

  • Hepatic portal vein: Supplies 80% of blood; carries nutrient-rich blood from the intestine.

  • Venous drainage: Achieved through three hepatic veins into the inferior vena cava (IVC).

Portal Triad

  • The hilum of the liver where structures enter/exit:

    • Portal vein, hepatic artery, and bile duct are included in this triad.

Liver Functions

  • Secretes bile.

  • Removes nutrients from blood.

  • Converts glucose to glycogen and stores it.

  • Stores iron and some vitamins.

  • Metabolizes proteins, fats, and carbohydrates.

  • Manufactures blood plasma proteins.

  • Detoxifies various substances.

  • Phagocytizes bacteria and weakened red blood cells (RBCs).

Sonographic Evaluation of the Liver

  • Indications for examination: Abdominal discomfort, abnormal liver function tests, jaundice, etc.

  • Patient preparation: NPO for 6-8 hours, avoid gas-inducing activities.

Scanning Techniques

  • Transducer Selection: Linear or curved; chosen based on body habitus.

  • Scanning procedure: Evaluate systematically in sagittal and transverse planes, paying attention to size, echotexture, and vascular supply.