Segments The lobes of the liver are further divided into eight
liver segments in the
Couinaud system. These are also known as hepatic segments that are
surgically resectable. The right lobe is of a somewhat quadrilateral form. Its under and posterior surfaces being marked by three fossæ: the fossa for the
portal vein, the fossa for the
gall-bladder and the fossae for the
inferior vena cava. These separate the right lobe into two smaller lobes on its left posterior part: the quadrate lobe and the caudate lobe.
Quadrate lobe The
quadrate lobe is an area of the
liver situated on the undersurface of the medial segment left lobe (Couinaud segment IVb), bounded in front by the anterior margin of the liver, behind by the
porta hepatis, on the right by the fossa for the
gall-bladder, and on the left by the fossa for the
umbilical vein. It is oblong in shape, its antero-posterior diameter being greater than its transverse.
Caudate lobe The
caudate lobe (
posterior hepatic segment I) is situated upon the posterosuperior surface of the liver on the right lobe of the liver, opposite the tenth and eleventh
thoracic vertebrae. The caudate lobe of the liver is bounded below by the
porta hepatis, on the right by the fossa for the
inferior vena cava, and on the left by the fossa for the
ductus venosus and the physiological division of the liver, called the
ligamentum venosum. It looks backward, being nearly vertical in position; it is longer from above downward than from side to side, and is somewhat concave in the transverse direction. It is situated behind the
porta, and separates the fossa for the
gall-bladder from the commencement of the fossa for the
inferior vena cava. See Adriaan van den Spiegel 1578-1625 Spiegel's lobe.
Budd–Chiari syndrome, caused by occlusion of hepatic venous outflow, can lead to hypertrophy of the caudate lobe due to its own caval anastomosis that allows for continued function of this lobe of the liver. The caudate lobe is named after the tail-shaped hepatic tissue (
cauda; Latin, "tail") papillary process of the liver, which arise from its left side. It also has a caudate process (that is not tail-like shaped) arising from its right side, which provides surface continuity between the caudate lobe and the visceral surface of the anatomical right lobe of the liver. Besides, the caudate lobe also derives its supply from the right and left branches of the portal vein. Its venous drainage is through short hepatic veins that drain directly into the inferior vena cava (IVC) due to its proximity to the IVC. == References ==