Hepatic lobes, segments, and subsegments

• It is important to know the location of the sub-segments of the liver. In order to perform segmental or subsegmental resection of the liver, the surgeon must know exactly which parts of the liver are diseased so that vascular supply and venous and biliary drainage can be preserved. Knowing the subsegments helps the radiologist communicate with the surgeon.
  
  
• The liver is divided into three functional lobes: the right lobe, the left lobe, and the caudate lobe.
  
  
• The right and left lobes are further divided into 2 segments each:
  • The anterior and posterior segments of the right lobe
  • The medial and lateral segments of the left lobe
    
    
• These 4 segments are further divided into 8 subsegments:
  • The superior anterior and superior posterior subsegments of the right lobe
  • The inferior anterior and inferior posterior subsegments of the right lobe
  • The superior medial and superior lateral subsegments of the left lobe
  • The inferior medial and inferior lateral subsegments of the left lobe
    
    
• The caudate lobe is positioned posteriorly and is separated from the remainder of the liver by the fissure for the ligamentum venosum.