“Is Life worth Living? It all depends on the Liver.” William James

1. Anatomical Divisions Of
Liver
DR MOHSIN KHAN

2. Liver
Liver is the largest organ in the body,
weighting 1.5 kg in the average 70-kg man. The
liver parenchyma is entirely covered by a thin
capsule and by visceral peritoneum on all except
the posterior surface of the liver termed the
“Bare Area”.
Liver is divided into a large right lobe, which
constitutes three-quarters of the liver
parenchyma, a quadrate lobe (present
undersurface of right lobe), a caudate lobe
(present on the postero-superior surface of right
lobe) and a left lobe.

3. Segmental Anatomy Of The Liver
Understanding the internal anatomy of
the liver has greatly facilitated safe liver
surgery.
Couinaud, a French anatomist, described
the liver as being divided into eight
segments.
Each of these segments can be
considered as a functional unit with a
branch of the hepatic artery, portal vein
and bile duct, and drained by a branch
of the hepatic vein.

4. Couinaud Classification
Right Hepatic Vein divides the right lobe into anterior
(V,Vlll) and posterior (VI,VII) segments.
Middle Hepatic Vein divides the liver into right and left
lobes ( right and left hemilivers ). This plane runs from the IVC
to the gallbladder fossa & known as Cantlie’s line.
Left Hepatic Vein divides the left lobe into medial (IV) and
lateral (II,lll) segments.

5. Couinaud Classification
A horizontal plane, known as the portal plane where portal vein
bifurcates and becomes horizontal, divides each section of liver
into the superior and inferior segments.
Left Lateral Section: Segment Il above and segment lll below
the portal plane
Left Medial Section: Segment IVA above and segment IVB
below the portal plane
Right Anterior Section: Segment Vlll above and segment V
below the portal plane
Right Posterior Section: Segment Vll above and segment VI
below the portal plane

6. Numbering Of Liver Segments
Segment l is the Caudate Lobe
 Bounded posterolaterally by the fossa for the
IVC, anteriorly by the ligamentum venosum
and inferiorly by the porta hepatis
 May receive its supply from both the right and
left portal veins
 Is drained directly into the IVC by one or more
small hepatic veins
The remainder of the Segments (ll-Vlll) are
numbered in a clockwise fashion starting
superiorly in the left hemiliver.

7. Numbering Of Liver Segments
Segment ll and lll are to the left of left hepatic vein and
falciform ligament with ll superior and lll inferior to the
portal plane
Segment IV lies between the left and middle hepatic
veins, it is subdivided into IV-A (superior) and IV-B
(inferior) segments. Segment IV also includes the
quadrate lobe.
Segments V-Vlll make up the right hemiliver and
describe as
Segment V is located between the right and middle
hepatic veins below the portal plane
Segment VI is located to the right of right hepatic vein
below the portal plane
Segment Vll is located to the right of right hepatic vein
above the portal plane
Segment Vlll is located between the right and middle
hepatic veins above the portal plane

8. Couinaud Classification System

9. Segmental Anatomy Of The Liver
The overall anatomy of the liver is divided into a functional right
and left ‘units along the line between the gall bladder fossa and
the middle hepatic vein (Cantlie’s line).
Liver segments(V-Vlll) to the the right of this line are supplied by
the right hepatic artery and the right branch of the portal vein, and
drain bile via the right hepatic duct.
Liver segments(II-IV) to the left of this line are supplied by the left
hepatic artery and the left branch of the portal vein, and drains bile
via the left hepatic duct.

10. Importance Of Segmental division Of Liver
The division of liver into self-contained
units allow the surgical resection of
individual segments and sections (two or
more adjacent segments) without
damaging remaining segments. Hence, for
the liver to remain viable, resection occurs
along the hepatic veins and portal veins in
the planes that define the boundaries of
these segments.

11. “Is Life worth
Living? It all
depends on
the Liver.”
William James
THANK YOU