Week 4 Ab

Liver Overview

  • Central organ in metabolism and homeostasis.

  • Segmental organ with complex structures and functions.

General Characteristics

  • Largest organ in the body, complex in structure.

  • A single liver cell can perform over 500 metabolic functions.

  • The liver contours vary with a patient's habitus.

  • Weighs approximately:

    • Birth: 150 g

    • Adult Male: 1.4 kg to 1.8 kg

    • Adult Female: 1.2 kg to 1.4 kg

  • Accessible for sonographic evaluation.

Anatomic Location

  • Positioned in multiple regions:

    • Right hypochondrium (mostly)

    • Greater part of the epigastrium

    • Part of the left hypochondrium

Anterior Relations

  • Henderson with:

    • Diaphragm

    • Right and left costal margins

    • Pleura of both lungs

    • Xiphoid process

    • Anterior abdominal wall

Posterior Relations

  • Interacts with:

    • Diaphragm

    • Right kidney

    • Hepatic flexure of the colon

    • Duodenum

    • Gallbladder

    • Inferior vena cava (IVC)

    • Esophagus

    • Fundus of stomach

Hepatic Recesses

  • Clinical importance due to potential fluid collection:

    1. Subphrenic spaces (left and right)

    2. Subhepatic space

    3. Morison's pouch (posterior to right lobe)

Subphrenic Spaces

  • Located between diaphragm and liver (on each side of falciform ligament).

Subhepatic Space

  • Positioned between the inferior surface of the liver and stomach.

Morison's Pouch

  • Between right liver lobe and right kidney, an important area for fluid accumulation.

Glisson’s Capsule

  • Comprises two layers:

    • Outer serous layer (visceral peritoneum)

    • Inner dense, fibroelastic layer (hyperechoic specular reflector).

Bare Area of Liver

  • Area directly contacting the diaphragm; lacks peritoneal covering.

Liver Ligaments

  • Ligaments connecting liver to diaphragm and abdominal walls:

    • Falciform ligament

    • Ligamentum teres (round ligament)

    • Coronary ligaments (left and right)

    • Ligamentum venosum (triangular ligament)

Falciform Ligament

  • Attaches liver's anterior surface to anterior abdominal wall.

  • Contains ligamentum teres, a remnant of umbilical vein.

Liver Lobes

  • Divided into major lobes for functional understanding:

    • Right lobe (largest)

    • Left lobe (smaller)

    • Caudate lobe (posterior aspect)

    • Quadrate lobe (inferior aspect)

Right Lobe

  • Exceeds left lobe by a 6:1 ratio.

  • Contains: Porta Hepatis, gallbladder fossa, and IVC fossa.

Left Lobe

  • Always smaller than the right, with considerable variability.

Caudate Lobe

  • Located on posterior-superior part of the liver.

  • Bordered by:

    • Porta Hepatis

    • IVC fossa

    • Ductus venosus fossa.

Quadrate Lobe

  • Positioned between gallbladder and round ligament fossa.

Liver Fissures

  • Plays a key role in separation of liver lobes:

    • Main lobar fissure separates right and left lobes.

    • Intersegmental fissures divide segments within lobes.

Cauinaud’s Liver Anatomy

  • Segmental anatomy described by Claude Cauinad.

  • Caudate lobe: segment 1,

    • Right lobe: segments 5, 6, 7, 8,

    • Left lobe: segments 2, 3, 4.

Dual Blood Supply of Liver

  • Hepatic artery (20%) and hepatic portal vein (80%) supply blood:

    • Hepatic artery provides oxygenated blood.

    • Portal vein provides nutrient-rich blood from gastrointestinal tract.

Venous Drainage

  • Blood drains through three major hepatic veins into IVC:

    • Left, middle, and right hepatic veins.

Portal Triad

  • Located at porta hepatis comprised of:

    • Portal vein

    • Hepatic artery

    • Bile duct.

Liver Functions

  • Various critical metabolic roles:

    • Secretes bile

    • Converts glucose to glycogen

    • Manuactures plasma proteins

    • Detoxifies drugs and pathogens

    • Stores nutrients like iron and vitamins.

Sonographic Evaluation of the Liver

  • Indications include:

    • Abdominal pain, fever, jaundice, monitoring conditions such as hepatomegaly, or evaluating tumors.

  • Patient prep involves NPO for 6-8 hours to reduce gas formation.

    • Techniques used during imaging include normal and deep suspended breathing to optimize liver exposure.

Normal Liver Ultrasonography Findings

  • Appearance:

    • Homogenous and gray-shaded, echogenicity comparable to kidney; typically less than pancreas or spleen.

  • Dimensions:

    • Normal liver length ranges from 13 cm to 17 cm.