human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

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 a multicellular organism, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization, hierarchy of life, an organ lies between Tissue (biology), tissue and an o ...

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 In human anatomy, the falciform ligament () is a ligament that attaches the liver to the front body wall and divides the liver into the left lobe and right lobe. The falciform ligament is a broad and thin fold of peritoneum, its base being dire ...

, 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'' (; ''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 t ...

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 (anatomy), organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath t ...

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 The ligamentum venosum, also known as Arantius' ligament, is the fibrous remnant of the ductus venosus of the fetal circulation. Usually, it is attached to the left branch of the portal vein within the porta hepatis. It may be continuous with the ...

and the round ligament of the liver (ligamentum teres), which further divide the left side of the liver in two sections. An important anatomical landmark, the

porta hepatis The porta hepatis or transverse fissure of the liver is a short but deep fissure, about 5 cm long, extending transversely beneath the left portion of the right lobe of the liver, nearer its posterior surface than its anterior border. It join ...

, 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, eac ...

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 fo ...

, and left

hypochondriac Hypochondriasis or hypochondria is a condition in which a person is excessively and unduly worried about having a serious illness. Hypochondria is an old concept whose meaning has repeatedly changed over its lifespan. It has been claimed that th ...

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

for the cranial (upper) half and by the ligamentum teres hepatis (

round ligament of liver The round ligament of the liver, 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 umbilical ...

) for the caudal (under) half. The ligamentum teres hepatis turns around the inferior margin of the liver to come out ventral in the

. 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. Approxima ...

, the fossa for the

gall-bladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow Organ (anatomy), organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath t ...

and the fossae for the

inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the ...

. 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

, on the right by the fossa for the

, 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 vo ...

. 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 vertebra (anatomy), vertebrae of intermediate size between the ce ...

. The caudate lobe of the liver is bounded below by the

, on the right by the fossa for the

, and on the left by the fossa for the ductus venosus and the physiological division of the liver, called the

. 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

from the commencement of the fossa for the

. See Adriaan van den Spiegel 1578-1625 Spiegel's lobe.

Budd–Chiari syndrome Budd–Chiari syndrome is a condition when an occlusion or obstruction in the hepatic veins prevent normal outflow of blood from the liver. The symptoms are non-specific and vary widely, but it may present with the classical triad of abdomin ...

, 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. The caudate lobe has a complex blood supply system. It derives its arterial supply from the caudate arteries, which arise from the right, left, and middle hepatic arteries that are connected to each other. 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

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