The document summarizes Couinaud's classification of liver segmental anatomy. It divides the liver into eight functionally independent segments, each with its own vascular inflow and outflow and biliary drainage. The right hepatic vein divides the right lobe into anterior and posterior segments. The middle hepatic vein divides the liver into right and left lobes. The left hepatic vein divides the left lobe into medial and lateral segments. The portal vein divides the liver into upper and lower segments.

1. Liver Segmental Anatomy
Hisham AlKhatib, M.D.
Consultant Radiologist

2. • Liver anatomy can be described using two
different aspects: morphological anatomy and
functional anatomy.
• The traditional morphological anatomy is based
on the external appearance of the liver and does
not show the internal features of vessels and
biliary ducts branching, which are of obvious
importance in hepatic surgery.
• C. Couinaud (1957) divided the liver into eight
functionally indepedent segments.

3. • Couinaud classification
– divides the liver into eight functionally indepedent
segments.
– Each segment has its own vascular inflow, outflow
and biliary drainage.
– In the centre of each segment there is a branch of
the portal vein, and bile duct.
– In the periphery of each segment there is vascular
outflow through the hepatic veins.

5. Couinaud classification
• Right hepatic vein
divides the right lobe
into anterior and
posterior segments.

6. Couinaud classification
• Middle hepatic vein
divides the liver into
right and left lobes (or
right and left hemiliver).
This plane runs from
the inferior vena cava to
the gallbladder fossa.

7. Couinaud classification
• Left hepatic vein divides
the left lobe into a medial
and lateral part.

8. Couinaud classification
• Portal vein
– divides the liver into
upper and lower
segments.
– The left and right portal
veins branch superiorly
and inferiorly to project
into the center of each
segment.

9. Segments numbering
• There are eight liver
segments.
• Segment 4 is sometimes
divided into segment 4a
and 4b according to
Bismuth.
• The numbering of the
segments is in a clockwise
manner .
• Segment 1 (caudate lobe)
is located posteriorly. It is
not visible on a frontal
view.
Clockwise numbering of the segments

11. LEFT: above the level of the left portal vein.
RIGHT: at the level of the left portal vein

12. LEFT: at the level of the right portal vein.
RIGHT: at the level of the splenic vein.

14. This figure is a transverse
image through the
superior liver segments,
that are divided by the
hepatic veins.

15. This figure shows transverse image
at the level of the left portal vein.
At this level the left portal vein
divides the left lobe of liver into
superior segments (2 and 4A) and
inferior segments (3 and 4B).

16. The image on the left is at the
level of right portal vein. At
this level right portal vein
divides the right lobe of the
liver into superior segments
(7 and 8) and the inferior
segments (5 and 6).
The level of right portal vein
is inferior to the level of left
portal vein

17. • below the level of the main
portal vein:
The gallbladder separates
segment(V) from segment
(IVB).
The ligamentum teres divides
segment(IVB) and (III)
segments.