Liver segment

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Liver segment
Liver 04 Couinaud classification animation.gif
Shape of human liver in animation. Eight segments by Couinaud labelled.
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Part of Liver
Anatomical terminology

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 transverse plane through the bifurcation of the main portal vein, [1] arranged in a clockwise manner starting from the caudate lobe.

Contents

Couinaud segments

Couinaud classification system Liver 04 Couinaud classification.svg
Couinaud classification system

There are four lobes of the liver. The Couinaud classification of liver anatomy then further divides the liver into eight functionally independent segments. Each segment has its own vascular inflow, outflow and biliary drainage. [2] In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct. In the periphery of each segment there is vascular outflow through the hepatic veins. [3] The division of the liver into independent units means that segments can be resected without damaging the remaining segments. [4] To preserve the viability of the liver following surgery, resections follow the vessels defining the peripheries of each segment. This means that resection lines parallel the hepatic veins, leaving the portal veins, bile ducts, and hepatic arteries intact. [1]

The classification system uses the vascular supply in the liver to separate the functional segments (numbered I to VIII)

Caudate lobe

Segment I is the caudate lobe and is situated posteriorly. It may receive its supply from both the right and the left branches of portal vein. It contains one or more hepatic veins which drain directly into the inferior vena cava (IVC). [1]

The caudate lobe is a separate structure which receives blood flow from both the right- and left-sided vascular branches. [5] [6]

The Caudate lobe includes: (1) the Spiegel lobe; (2) the paracaval portion; and (3) the caudate process portion. The Spiegel lobe has its portal venous and biliary branches ramified mainly from the left-side tract. The Paracaval portion has the portal venous branches ramified mainly from the left portal vein, while the biliary branches of this portion drained into the right and left biliary tracts at almost equal frequencies. The portal venous branches & Biliary branches of the caudate process portion has it ramified from the right-side tract.

Left lobe

Segments II and III lie medial to the falciform ligament with II superior to the portal venous supply and III inferior. Segment IV lies lateral to the falciform ligament and is subdivided into IVa (superior) and IVb (inferior). [7]

Right lobe

Segments V to VIII make up the right part of the liver: [3]

Quadrate lobe

The fissure for the round ligament of the liver (ligamentum teres) separates the medial and lateral parts of segment IV. The inferior medial segment (IVb) is also called the quadrate lobe. [8]

Society

The clockwise numbering of liver segments in Couinaud's classification is said to have been inspired by the numbering of arrondissements (administrative districts) of Paris. [9]

Related Research Articles

Articles related to anatomy include:

<span class="mw-page-title-main">Portal vein</span> Short thick vein formed by the union of the superior mesenteric vein and the splenic 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. Approximately 75% of total liver blood flow is through the portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins.

<span class="mw-page-title-main">Inferior vena cava</span> One of two veinous trunks bringing deoxygenated blood back to the heart

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 fifth lumbar vertebra.

<span class="mw-page-title-main">Umbilical vein</span> Vein running from the placenta to the fetus

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 volume and for administration of glucose and drugs.

<span class="mw-page-title-main">Portal hypertension</span> Abnormally increased portal venous pressure

Portal hypertension is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5–9 mmHg; clinically significant portal hypertension is present at portal pressures greater than 10 mmHg. The portal vein and its branches supply most of the blood and nutrients from the intestine to the liver.

<span class="mw-page-title-main">Common hepatic duct</span> Exocrine duct

The common hepatic duct is the first part of the biliary tract. It joins the cystic duct coming from the gallbladder to form the common bile duct.

<span class="mw-page-title-main">Pringle manoeuvre</span> Surgical technique

The Pringle manoeuvre is a surgical technique used in some abdominal operations and in liver trauma. The hepatoduodenal ligament is clamped either with a surgical tool called a haemostat, an umbilical tape or by hand. This limits blood inflow through the hepatic artery and the portal vein, controlling bleeding from the liver. It was first published by and named after James Hogarth Pringle in 1908.

<span class="mw-page-title-main">Hepatic veins</span> One of two sets of veins connected to the liver

In human anatomy, the hepatic veins are the veins that drain venous blood from the liver into the inferior vena cava. There are usually three large upper hepatic veins draining from the left, middle, and right parts of the liver, as well as a number (6-20) of lower hepatic veins. All hepatic veins are valveless.

<span class="mw-page-title-main">Transjugular intrahepatic portosystemic shunt</span> Artificial channel within the liver

Transjugular intrahepatic portosystemic shunt is an artificial channel within the liver that establishes communication between the inflow portal vein and the outflow hepatic vein. It is used to treat portal hypertension which frequently leads to intestinal bleeding, life-threatening esophageal bleeding and the buildup of fluid within the abdomen (ascites).

<span class="mw-page-title-main">Falciform ligament</span> Ligament attaching the liver to the front body wall

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 directed downward and backward and its apex upward and forward. It droops down from the hilum of the liver.

<span class="mw-page-title-main">Hepatic portal system</span> System of veins comprising the hepatic portal vein and its tributaries

In human anatomy, the hepatic portal system or portal venous system is the system of veins comprising the portal vein and its tributaries. The other portal venous systems in the body are the renal portal system, and the hypophyseal portal system.

<span class="mw-page-title-main">Round ligament of liver</span> Attaches the liver to the abdominal wall

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 vein. The round ligament divides the left part of the liver into medial and lateral sections.

<span class="mw-page-title-main">Porta hepatis</span> Short deep depression on the liver

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.

In the course of the round ligament of the liver, small paraumbilical veins are found which establish an anastomosis between the veins of the anterior abdominal wall and the portal vein, hypogastric, and iliac veins. These veins include Burrow's veins, and the veins of Sappey – superior veins of Sappey and the inferior veins of Sappey.

A portacaval anastomosis or portocaval anastomosis is a specific type of circulatory anastomosis that occurs between the veins of the portal circulation and the vena cava, thus forming one of the principal types of portasystemic anastomosis or portosystemic anastomosis, as it connects the portal circulation to the systemic circulation, providing an alternative pathway for the blood. When there is a blockage of the portal system, portocaval anastomosis enables the blood to still reach the systemic venous circulation. The inferior end of the esophagus and the superior part of the rectum are potential sites of a harmful portocaval anastomosis.

<span class="mw-page-title-main">Portal venous system</span> The capillary bed pools into another through veins without first going through the heart

In the circulatory system of vertebrates, a portal venous system occurs when a capillary bed pools into another capillary bed through veins, without first going through the heart. Both capillary beds and the blood vessels that connect them are considered part of the portal venous system.

<span class="mw-page-title-main">Liver</span> Vertebrate organ involved in metabolism

The liver is a major metabolic organ only found in vertebrate animals, 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 is located in the right upper quadrant of the abdomen, below the diaphragm and mostly shielded by the lower right rib cage. Its other metabolic roles include carbohydrate metabolism, the production of hormones, conversion and storage of nutrients such as glucose and glycogen, and the decomposition of red blood cells.

<span class="mw-page-title-main">Cantlie line</span> Anatomical line dividing the liver

In human anatomy, the Cantlie line or Cantlie's line is an imaginary division of the liver. The division divides the liver into two planes, extending from the middle hepatic vein to the middle of the gallbladder. It is useful for performing hepatectomies.

Radiation lobectomy is a form of radiation therapy used in interventional radiology to treat liver cancer. It is performed in patients that would be surgical candidates for resection, but cannot undergo surgery due to insufficient remaining liver tissue. It consists of injecting small radioactive beads loaded with yttrium-90 into the hepatic artery feeding the hepatic lobe in which the tumor is located. This is done with the intent of inducing growth in the contralateral hepatic lobe, not dissimilarly from portal vein embolization (PVE).

<span class="mw-page-title-main">Lobes of liver</span> Four gross divisions of the human liver

In human anatomy, the liver 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 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.

References

  1. 1 2 3 "Couinaud classification | Radiology Reference Article". Radiopaedia.org. Retrieved 2015-06-26.
  2. ↑ Kapoor, Vinay Kumar (14 September 2017). "Liver Anatomy: Overview, Gross Anatomy, Microscopic Anatomy". Medscape.
  3. 1 2 "The Radiology Assistant : Anatomy of the liver segments". Radiologyassistant.nl. 2006-05-07. Retrieved 2015-06-26.
  4. ↑ "Hepatic segments (Couinaud classification) / Radiological classifications commonly used on medical imaging / Radiology / Channels / e-Cases /". IMAIOS.com. Retrieved 2015-06-26.
  5. ↑ "Three-dimensional Anatomy of the Couinaud Liver Segments" . Retrieved 2009-02-17.
  6. ↑ Strunk, H.; Stuckmann, G.; Textor, J.; Willinek, W. (2003). "Limitations and pitfalls of Couinaud's segmentation of the liver in transaxial Imaging". European Radiology. 13 (11): 2472–82. doi:10.1007/s00330-003-1885-9. PMID   12728331.
  7. ↑ Sibulesky, Lena (March 2013). "Normal liver anatomy". Clinical Liver Disease. 2 (S1): S1–S3. doi: 10.1002/cld.124 . PMC   6448666 .
  8. ↑ Germain, T.; Favelier, S.; Cercueil, J.-P.; Denys, A.; Krausé, D.; Guiu, B. (November 2014). "Liver segmentation: Practical tips". Diagnostic and Interventional Imaging. 95 (11): 1003–1016. doi:10.1016/j.diii.2013.11.004. PMID   24388431.
  9. ↑ Majno, Pietro; Mentha, Gilles; Toso, Christian; Morel, Philippe; Peitgen, Heinz O.; Fasel, Jean H. D. (2014-03-01). "Anatomy of the liver: An outline with three levels of complexity – A further step towards tailored territorial liver resections". Journal of Hepatology. 60 (3): 654–662. doi: 10.1016/j.jhep.2013.10.026 . ISSN   0168-8278.
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