Liver segment: Difference between revisions

Revision as of 18:17, 25 February 2019

Latest revision as of 09:30, 4 June 2025

(24 intermediate revisions by 20 users not shown)

Line 1:

{{Short description|Anatomical unit of the liver}}

{{Infobox anatomy

| Name = Liver segment

| Image = Liver 04 Couinaud classification animation.svggif

| Caption = Shape of human liver in animation. Eight segments by Couinaud labelled.

| Caption = Couinaud classification system

| Width = 200px

| Image2 =

| Caption2 =

| PartOf = [[Liver]]

| Latin =

| Greek =

Line 13 ⟶ 15:

| Vein =

| Nerve =

| Lymph =

}}

InA '''liver segment''' is one of eight segments of the liver as described in the widely used Couinaud classification (named after [[Claude Couinaud|Couinaud]] (or "French") systemin ofthe [[anatomy]] of the '''[[liver]]''',. theThis functionalsystem lobesdivides arethe further[[lobes dividedof intoliver|lobes aof totalthe ofliver]] into eight subsegmentssegments based on a [[transverse plane]] through the [[wikt:bifurcation|bifurcation]] of the main [[portal vein.]],<ref name="radiopaedia.org">{{cite web|url=http://radiopaedia.org/articles/couinaud-classification |title=Couinaud classification &#124; Radiology Reference Article |publisher=Radiopaedia.org |accessdate=2015-06-26}}</ref> Thearranged systemin isa namedclockwise aftermanner [[Claudestarting from Couinaud]]the caudate lobe.

==Couinaud segments==

==Segments==

[[File:Liver 04 Couinaud classification animation.gifsvg|thumb|Shapeleft|upright=2|Couinaud ofclassification human liver in animation. Eight subsegments by Couinaud labelled.system]]

TheThere fissureare for thefour [[round ligamentLobes of liver|round ligamentlobes of the liver]] (ligamentum teres) also separates the medial and lateral segments. The medialCouinaud segmentclassification isof alsoliver calledanatomy thethen [[quadratefurther lobe]]. Individes the widely used [[Claude Couinaud|Couinaud]] (or "French") system, the functional lobes are further dividedliver into a total of eight subsegmentsfunctionally basedindependent onsegments. aEach transversesegment planehas throughits theown bifurcationvascular ofinflow, theoutflow mainand portalbiliary veindrainage.<ref name="radiopaedia.org">{{cite web |urllast1=http://radiopaedia.org/articles/couinaud-classificationKapoor |titlefirst1=CouinaudVinay classification &#124; Radiology Reference ArticleKumar |publishertitle=Radiopaedia.orgLiver |accessdate=2015-06-26}}</ref>Anatomy: Overview, TheGross [[caudateAnatomy, lobe]]Microscopic is a separate structure which receives blood flow from both the right- and left-sided vascular branches.<ref name="3d">{{cite webAnatomy |url=httphttps://dpiemedicine.radiologymedscape.uiowa.educom/nlmarticle/app/livertoc/liver/liver.html |title=Three1900159-dimensional Anatomy of the Couinaud Liver Segmentsoverview |accessdatewebsite=2009-02-17}}</ref><ref name="strunk">{{cite journalMedscape |last1date=Strunk14 |first1=H. |last2=Stuckmann |first2=G. |last3=Textor |first3=J. |last4=Willinek |first4=W. |title=Limitations and pitfalls of Couinaud's segmentation of the liver in transaxial Imaging |journal=European Radiology |volume=13 |issue=11 |pages=2472–82 |year=2003 |pmid=12728331 |doi=10.1007/s00330-003-1885-9September 2017}}</ref> The Couinaud classification of liver anatomy divides the liver into eight functionally independent segments. Each segment has its own vascular inflow, outflow and biliary drainage. 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.<ref name="radiologyassistant.nl">{{cite web|url=http://www.radiologyassistant.nl/en/p4375bb8dc241d/anatomy-of-the-liver-segments.html |title=The Radiology Assistant : Anatomy of the liver segments |publisher=Radiologyassistant.nl |date=2006-05-07 |accessdate=2015-06-26}}</ref> The division of the liver into independent units means that segments can be resected without damaging the remaining segments.<ref>{{cite web|url=https://www.imaios.com/en/e-Cases/Channels/Radiology/Radiological-classifications-commonly-used-on-medical-imaging/Hepatic-segments-Couinaud-classification |title=Hepatic segments (Couinaud classification) / Radiological classifications commonly used on medical imaging / Radiology / Channels / e-Cases / |publisher=IMAIOS.com |accessdate=2015-06-26}}</ref> 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.<ref name="radiopaedia.org"/>

The classification system uses the vascular supply in the liver to separate the functional segments (numbered {{rn|I}} to {{rn|VIII}}):

*Segment I is the caudate lobe and is situated posterior l and 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]].<ref name="radiopaedia.org"/>

===Caudate lobe===

The remainder of the segments (II to VIII) are numbered in a clockwise fashion:<ref name="radiologyassistant.nl"/>

*Segment {{rn|I}} is the caudate lobe and is situated posteriorposteriorly. l and itIt 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 [[Inferiorinferior vena cava|IVC]] (IVC).<ref name="radiopaedia.org"/>

*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)

The [[caudate lobe]] is a separate structure which receives blood flow from both the right- and left-sided vascular branches.<ref name="3d">{{cite web |url=http://dpi.radiology.uiowa.edu/nlm/app/livertoc/liver/liver.html |title=Three-dimensional Anatomy of the Couinaud Liver Segments |accessdate=2009-02-17}}</ref><ref name="strunk">{{cite journal |last1=Strunk |first1=H. |last2=Stuckmann |first2=G. |last3=Textor |first3=J. |last4=Willinek |first4=W. |title=Limitations and pitfalls of Couinaud's segmentation of the liver in transaxial Imaging |journal=European Radiology |volume=13 |issue=11 |pages=2472–82 |year=2003 |pmid=12728331 |doi=10.1007/s00330-003-1885-9 }}</ref>

Segments V to VIII make up the right part of the liver:<ref name="radiologyassistant.nl"/>

*segment V is the most medial and inferior

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.

*segment VI is located more posteriorly

*segment VII is located above segment VI

===Left lobe===

*segment VIII sits above segment V in the superio-medial position

Segments {{rn|II}} and {{rn|III}} lie [[Lateral (anatomy)|medial]] to the falciform ligament with {{rn|II}} superior to the portal venous supply and {{rn|III}} inferior. Segment {{rn|IV}} lies [[Medial (anatomy)|lateral]] to the falciform ligament and is subdivided into {{rn|IVa}} (superior) and {{rn|IVb}} (inferior).<ref>{{cite journal |last1=Sibulesky |first1=Lena |title=Normal liver anatomy |journal=Clinical Liver Disease |date=March 2013 |volume=2 |issue=S1 |pages=S1–S3 |doi=10.1002/cld.124|doi-access=free|pmc=6448666}}</ref>

===Right lobe===

Segments {{rn|V}} to {{rn|VIII}} make up the right part of the liver:<ref name="radiologyassistant.nl"/>

*segmentSegment {{rn|V}} is the most medial and inferior

*segmentSegment {{rn|VI}} is located more posteriorly

*segmentSegment {{rn|VII}} is located above segment {{rn|VI}}

*segmentSegment {{rn|VIII}} sits above segment {{rn|V}} in the superiosuperior-medial position

===Quadrate lobe===

The [[fissure (anatomy)|fissure]] for the [[round ligament of liver|round ligament of the liver]] (ligamentum teres) separates the [[Medial (anatomy)|medial]] and lateral parts of segment {{rn|IV}}. The inferior medial segment ({{rn|IVb}}) is also called the [[quadrate lobe]].<ref>{{cite journal |last1=Germain |first1=T. |last2=Favelier |first2=S. |last3=Cercueil |first3=J.-P. |last4=Denys |first4=A. |last5=Krausé |first5=D. |last6=Guiu |first6=B. |title=Liver segmentation: Practical tips |journal=Diagnostic and Interventional Imaging |date=November 2014 |volume=95 |issue=11 |pages=1003–1016 |doi=10.1016/j.diii.2013.11.004|doi-access=|pmid= 24388431}}</ref>

== Society ==

The clockwise numbering of liver segments in Couinaud's classification is said to have been inspired by the numbering of [[Arrondissements of Paris|arrondissements (administrative districts) of Paris]].<ref>{{Cite journal |last=Majno |first=Pietro |last2=Mentha |first2=Gilles |last3=Toso |first3=Christian |last4=Morel |first4=Philippe |last5=Peitgen |first5=Heinz O. |last6=Fasel |first6=Jean H. D. |date=2014-03-01 |title=Anatomy of the liver: An outline with three levels of complexity – A further step towards tailored territorial liver resections |url=https://www.sciencedirect.com/science/article/pii/S0168827813007526 |journal=Journal of Hepatology |volume=60 |issue=3 |pages=654–662 |doi=10.1016/j.jhep.2013.10.026 |issn=0168-8278|doi-access=free }}</ref>

==References==

{{reflist}}

==External links==

* [https://radiopaedia.org/articles/couinaud-classification-of-hepatic-segments] [[Radiopaedia]] overview

{{Accessory digestive glands}}