Anatomía - Segmentación Hepática (Lìnea de Cantlié y División Fisiológica del Hígado)

Segmentation of the Liver

The discussion focuses on the hepatic segmentation, emphasizing the importance of understanding the liver's division into segments for both anatomical and surgical purposes.

Hepatic Segmentation Overview

• Historically, the liver was divided into right, left, square, and caudate lobes based on the falciform ligament. However, this division was inaccurate in terms of vascular supply.

• The liver is composed of 8 segments (sometimes 9), each supplied by its own portal triad consisting of the hepatic artery, portal vein, and bile duct. This segmentation allows for independent functioning of each segment.

• Understanding hepatic segmentation is crucial in surgery as removing one or more segments can be done without affecting blood supply or bile drainage to other segments. This is significant in conditions like hepatocellular carcinoma.

Importance of Hepatic Segmentation

• Each liver segment functions independently like a mini-liver. This knowledge aids in surgical procedures where selective removal of segments is required without compromising overall liver function.

• Hepatic segmentation involves three major portal fissures within the liver parenchyma: right portal fissure, left portal fissure, and main portal fissure. These are essential for dividing the liver accurately.

Anatomical References for Segmentation

• Major portal fissures are true intraparenchymal grooves housing important veins such as hepatic veins draining into the inferior vena cava. These serve as landmarks for accurate liver division.

• Anatomical structures like these fissures aid anatomists and surgeons in emulating the path of hepatic veins within the liver from an external perspective to facilitate precise organ segmentation.

Liver Division Techniques

Exploring how anatomists and surgeons utilize specific anatomical references to divide the liver accurately into segments for various medical procedures.

Utilizing Anatomical Landmarks

• Anatomists rely on reference structures to mimic paths of hepatic veins within the liver from an external view. Key structures like major portal fissures guide accurate organ division.

• The principal portal fissure follows the course of middle hepatic vein aiding in dividing the liver into right and left lobes. Kant's line serves as an imaginary reference line crucial for this purpose.

Liver Division Techniques

• Kant's line extends from porta hepatis towards the left edge of inferior vena cava along with middle hepatic vein trajectory. This line divides the liver into right and left lobes facilitating further segmentation based on additional portals.

• By incorporating major portal fissures (right & left), surgeons can delineate sectors within right and left lobes enabling precise localization during surgical interventions.

Segmenting the Liver for Surgical Purposes

In this section, the speaker discusses how to divide the liver into segments for surgical procedures based on anatomical structures.

Dividing the Liver into Sectors

• The left side of the liver is divided into a medial left sector and a lateral left sector.

• The right portal fissure is determined by drawing a line from the right end of the lower edge of the liver towards the hepatic hilum.

Segmentation of Liver Lobes

• The right liver lobe is divided into medial and lateral sectors by the right portal fissure.

• Similarly, the left liver lobe is divided into medial and lateral sectors by the left portal fissure.

Formation of Liver Segments

• Eight liver segments are formed following the bifurcation of the portal vein within each sector.

• The segments are numbered spirally starting with segment 1 (caudate lobe), moving counterclockwise in visceral view.

Understanding Hepatic Segmentation Terminology

This part delves into clarifying hepatic segmentation terminology and discussing specific liver lobes.

Clarification of Lobe Terms

• The speaker highlights that terms like "right lobe," "left lobe," "caudate lobe," and "quadrate lobe" are incorrect.

Role of Caudate Lobe

• The caudate lobe receives vascular supply and biliary drainage from both branches, leading to its classification as a separate entity.

Division of Right and Left Lobes

• Due to anatomical features like portal fissures, both right and left lobes are further divided into medial and lateral sectors.

Segment Allocation in Sectors