GI Radiology > Liver > Anatomy > Segment Separation

Liver Anatomy

How are the segments spatially separated?

  • The hepatic veins lie between segments whereas the portal vein lies within segments. Exception: the left portal vein does not lie within segments. These vessels play an important radiological role because they aid radiologists in approximately localizing a particular lesion to the correct anatomical section of the liver.

      
AP View of the Liver  (3D)                                               Axial View of the Liver (3D)

  • Cephalad in the liver, above the level of the main portal vein:
    • The middle hepatic vein separates the right lobe from the left lobe, or to be more specific, the right lobe, superior anterior subsegment (VIII), from the left lobe, superior medial subsegment (IVA).
    • The right hepatic vein separates the superior anterior (VIII) and superior posterior (VII) subsegments of the right lobe.
    • The left hepatic vein separates the superior medial (IVA) and superior lateral (II) subsegments of the left lobe.

            
AP View of the Liver  (3D)                                               Axial View of the Liver (2D)

  • At the level just above the main portal vein:
    • The left portal vein separates the superior medial (IVA) subsegment from the superior lateral (II) subsegment of the left lobe.

            
AP View of the Liver  (3D)                                               Axial View of the Liver (2D)

  • Caudal in the liver, below the level of the main portal vein:
    • The line that bisects the angle between the anterior and posterior branches of the right portal vein separates the inferior anterior (V) and inferior posterior (VI) subsegments of the right lobe. First, you need to identify the right portal vein. Then, the anterior branch will go into the inferior anterior subsegment (V) while the posterior branch will go towards the inferior posterior subsegment (VI).

             
AP View of the Liver  (3D)                                               Axial View of the Liver (2D)

  • The gallbladder separates the right lobe, inferior anterior subsegment (V) from the left lobe, inferior medial subsegment (IVB).
  • The ligamentum teres divides the left lobe into the inferior medial (IVB) and inferior lateral (III) subsegments.

                
AP View of the Liver  (3D)                                                  Axial View of the Liver (2D)

 

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