human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a hea ...

, the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

is divided grossly into four parts or lobes: the right lobe, the left lobe, the caudate lobe, and the quadrate lobe. Seen from the front – the diaphragmatic surface - the liver is divided into two lobes: the right lobe and the left lobe. Viewed from the underside – the

visceral In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

surface, the other two smaller lobes the caudate lobe, and the quadrate lobe are also visible. The two smaller lobes, the caudate lobe and the quadrate lobe, are known as superficial or accessory lobes, and both are located on the underside of the right lobe. The falciform ligament, visible on the front of the liver, makes a superficial division of the right and left lobes of the liver. From the underside, the two additional lobes are located on the right lobe. A line can be imagined running from the left of the

vena cava In anatomy, the venae cavae (; singular: vena cava ; ) are two large veins (great vessels) that return deoxygenated blood from the body into the heart. In humans they are the superior vena cava and the inferior vena cava, and both empty into th ...

and all the way forward to divide the liver and

gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...

into two halves. This line is called Cantlie's line and is used to mark the division between the two lobes. Other anatomical landmarks exist, such as the ligamentum venosum and the

round ligament of the liver The round ligament of the liver (or ligamentum teres, or ligamentum teres hepatis) is a ligament that forms part of the free edge of the falciform ligament of the liver. It connects the liver to the umbilicus. It is the remnant of the left umbi ...

(ligamentum teres), which further divide the left side of the liver in two sections. An important anatomical landmark, the porta hepatis, also known as the ''transverse fissure of the liver'', divides this left portion into four segments, which can be numbered in

Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, ...

starting at the caudate lobe as I in an anticlockwise manner. From this parietal view, seven segments can be seen, because the eighth segment is only visible in the visceral view. Labeled human liver

Structure

Segments

The lobes of the liver are further divided into eight

liver segment A liver segment is one of eight segments of the liver as described in the widely used Couinaud classification (named after Claude Couinaud) in the anatomy of the liver. This system divides the lobes of the liver into eight segments based on a ...

s in the Couinaud system. These are also known as hepatic segments that are surgically resectable.

Left lobe

The left lobe is smaller and more flattened than the right. It is situated in the

epigastric In anatomy, the epigastrium (or epigastric region) is the upper central region of the abdomen. It is located between the costal margins and the subcostal plane. Pain may be referred to the epigastrium from damage to structures derived from the f ...

, and left

hypochondriac Hypochondriasis or hypochondria is a condition in which a person is excessively and unduly worried about having a serious illness. An old concept, the meaning of hypochondria has repeatedly changed. It has been claimed that this debilitating cond ...

regions of the abdomen. Its upper surface is slightly convex and is moulded on to the diaphragm; its under surface presents the gastric impression and omental tuberosity.

Right lobe

The right lobe is six times the size of the left lobe. It occupies the right hypochondrium, on its posterior surface by the ligamentum venosum for the cranial (upper) half and by the ligamentum teres hepatis ( Round ligament of liver) for the caudal (under) half. The

ligamentum teres hepatis The round ligament of the liver (or ligamentum teres, or ligamentum teres hepatis) is a ligament that forms part of the free edge of the falciform ligament of the liver. It connects the liver to the umbilicus. It is the remnant of the left umbil ...

turns around the inferior margin of the liver to come out ventral in the falciform ligament. The right lobe is functionally separated from the left lobe by the middle hepatic vein. From a functional perspective (one that takes the arterial, portal venous, and systemic venous anatomy into account) the falciform ligament separates the medial and lateral segments of the left hepatic lobe. 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 portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approx ...

, 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

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 The umbilical vein is a vein present during fetal development that carries oxygenated blood from the placenta into the growing fetus. The umbilical vein provides convenient access to the central circulation of a neonate for restoration of blood v ...

. 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 In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

. 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 Budd–Chiari syndrome is a very rare condition, affecting one in a million adults. The condition is caused by occlusion of the hepatic veins that drain the liver. It presents with the classical triad of abdominal pain, ascites, and liver enlar ...

, 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. The caudate process is a small elevation of the hepatic substance extending obliquely and laterally, from the lower extremity of the caudate lobe to the undersurface of the right lobe.

References

External links

* * - "The Visceral Surface of the Liver" * * * * * - "Abdominal Cavity: Inspection of the Abdominal Viscera in situ" * - "The Visceral Surface of the Liver" * {{Portal bar, Anatomy