1) Segment 1 lies between the inferior vena cava, ligamentum venosum, and left branch of the portal vein. It is unique in receiving branches from both the right and left portal veins and draining directly into the inferior vena cava. 2) Segments 2 and 3 form the lateral part of the left lobe and are located to the left of structures including the umbilical portion of the portal vein and falciform ligament. 3) Segment 4, also known as the quadrate lobe or medial segment of the left lobe, is bounded by structures including the umbilical portion of the left portal vein and falciform ligament. It is subdivided into segments

1. Ultrasound evaluation of liver segments
Dr. Durr-e-Sabih. MBBS.MS. FRCP. FANMB
Multan ultrasound Service- Distt Jail Road- Multan Pakistan. dsabih@yahoo.com
Segment Segment 1 lies between the inferior vena cava; the ligamentum
venosum and the left branch of portal vein. It is unique that it can
receive branches from both the right as well as left portal veins and has
hepatic veins that drain directly into the inferior vena cava. It is quite
easy to identify on ultrasound.
On a transverse section ,this can have a quadrilateral shape but on a
sagittal section, it is more wedge shaped.
1,2,3
2,3
Segments 2 and 3 form the lateral part of the left lobe and are located
to the left of the umbilical portion of the portal vein, the ligamentum
venosum and the falciform ligament.
4
This is the quadrate lobe, or the medial segment of the left lobe in
classical anatomy and is located on both sides of the horizontal portion
of the left portalvein (pars transversa). Boundaries include the
umbilical portion of the left portal vein and the falciform ligament
separating it from segments 2 and 3; the ligamentum venosum
separates it from segment 1 posteriorly. Laterally the middle hepatic
vein and the main hepatic hepatic fissure separates this from the right
lobe segments 5 and 8. Segment 4 is itself subdivided into a superiorly
located segment 4A and inferiorly located segment 4B by the
horizontal segment of the left portal vein (pars transvera).
5-8
Segments 5 - 8 make up the right lobe and are further divided into
anterior (5 and 8) and posterior sub-sets (6 and 7). The right hepatic
vein forms the boundary between the anterior and posterior subsets,
and a line from the right portal vein divides the segments into superior
(7 and 8) and inferior (5 and 6) sub-sets. The intersegmental
boundaries are not anatomical and this makes right lobe segment
identification somewhat difficult.
5
Segment 5 appears on a longitudinal section immediately to the right
of the main portal vein, and in some patients can include the part of
liver in front of the gallbladder, but since the fundus of the gallbladder
can have in inconstant position, this relationship cannot be assumed in
every patient.
6
This lies behind and lateral to segment 5 and is right in front of the
right kidney; so whenever you are seeing the right kidney; the liver
immediately anterior to it is segment 6.
7
This lies cranial to segment 6 and forms the anterolateral part of the
dome of the right lobe of the liver. Lateral and posterior to the right
hepatic vein Between the right hepatic vein and the diaphragm
8
Cranial to segment 5
The segments are distribution in different planes in the liver volume,
with segment 1 being completely posterior and segments 6 and 7
being mostly posterior. The ligaments in the fissures, portal and hepatic vessels are used to locate the
segments.
The portal vein branches run to the centre of the segments except the ascending branch of the left portal
vein, that runs in the left intersegmental fissure; helping to divide the medial from the lateral part of the left
lobe, segment 3 from segment 4
Segments on Transverse sections