门静脉分支在肝脏内的分枝和分布，伴随着肝动脉和胆管的分支，遵循一个相当恒定的组织机构，尽管放射科医生和外科医生应该考虑变异的存在。
原文:
The division and distribution ofthe branches of the portal vein within the liver, accompanied by ramificationsof the hepatic artery and the bile ducts, follows a quite constantorganization, although variants[9, 10]should be taken into account by radiologists and surgeons.
因此，可以在肝脏内描述一些肝区或肝段，这是Couinaud的经典描述;这些部分拥有独立于邻近区域的血液供应和胆道引流，允许部分切除该器官。门静脉是主要的传入血管，它分为两支，分别供应肝脏的右侧和左侧。在器官的内脏表面，有一条线表示左右两个区域，从胆囊状窝到下腔静脉的左边缘(Cantlie’s线)。两个主要的门静脉分支依次分为二级分支：如图所示，左分支发出一只侧枝、一只旁枝和一只尾叶枝；右分支口径较大，分为侧支和旁支，各有前支和后支。四个扇区以如下的方式被划分：两个右侧扇区，左侧扇区和中间扇区，然后这两个区域又可以进一步分为两个左侧区和中间区。在这些区域中，三条肝静脉沿着称为门裂的垂直面走行：右门裂、主（中）门裂、左门裂。门脉分支的进一步细分，每一节产生两段；静脉分布于更局限的实质部分，没有交换吻合。因此，我们描述了肝脏的八个功能独立的段（图1.4）。
原文:
It is therefore possibleto describe within the liver some hepatic territories or sectors, classicallydescribed by Couinaud [11]; these sectors possess blood supply and biliarydrainage independent of neighboring territories, allowing a partial surgicalresection of the organ. The portal vein, the main afferent vessel, divides intotwo branches that supply the right side and the left side of the liver. On thevisceral surface of the organ, a line identifies the left and rightterritories, going from the cystic fossa to the left margin of the inferiorvena cava (Cantlie’s line). The two main portal branches in turn divide intosecondary branches: schematically, the left branch gives rise to a lateral anda paramedian branch, and a branch for the caudate lobe; the right branch, oflarger caliber, divides into the lateral and the paramedian branches, eachgiving front and rear branches. Four sectors are thusdistinguished: two right sectors, lateral and medial, and two left lateral andmedial sectors. Among these sectors the three hepatic veins run followingvertical planes called portal fissures: right portal fissure, main (middle) portalfissure, left portal fissure. The further subdivision of the portalbranches gives rise to two segments for each sector; veins distribute to morerestricted parts of the parenchyma, without exchanging anastomoses. Thus, wedescribe eight functionally independent segments of the liver [12](Fig. 1.4).
I段：它对应于尾状叶。与IV段相比，它位于更背部位置，与II段相邻，而在右侧，它包裹着下腔静脉。根据不同的分类，在该段内可识别出两个或三个区域，接受血管主要来自门静脉左支，部分也来自右支。传出静脉直接流入下腔静脉。胆管通常流入左肝管，非常接近右肝管的汇合点。
原文:
Segment I. It correspondsto the caudate lobe. It is in a dorsal position compared to segment IV , andadjacent to segment II, while on the right it enfolds the inferior vena cava.According to different classifications, two or three territories can berecognize within the segment, receiving vessels mainly from the left branch ofthe portal vein, and partly also from the right one. The efferent veins draindirectly into the inferior vena cava. The bile ducts usually flow into the lefthepatic duct very close to the point of confluence with the right one.
Ⅱ段：位于左肝门裂的外侧，位于肝左叶的上外侧位置。
原文:
Segment II. It is locatedlaterally to the left portal fissure in a superior-lateral position in the leftlobe of the liver.
Ⅲ段：位于脐裂左侧，位于肝左叶下外侧位置。它从一到两个左门静脉分支接受血液，但也可以从一个小的右分支接受血液。它会流入肝左静脉。
原文:
Segment III. It is on theleft of the umbilical fissure, in an inferior-lateral position of the left lobeof the liver. It receives blood from one to two left portal branches, but itcan also receive from a small right branch. It drains into the left hepaticvein.
Ⅳ段位于尾状叶前、脐裂右侧、门静脉主裂或中裂内侧。它由门静脉右支供血，偶尔也有小的左支供血，然后引流到中肝静脉。区分上部和下部，分别为IVa和IVb。
原文:
Segment IV . Located infront of the caudate lobe, at the right of the umbilical fissure and mediallyto the main or middle portal fissure. It is supplied with blood from the rightbranch of the portal vein and only occasionally also from a small left branch,and drains into the mean hepatic vein. An upper and a lower part aredistinguished, respectively IVa and IVb.
V段：位于肝中静脉和右肝静脉之间的前下方位置，血液从肝实质流出。它由右门脉分支供血。
原文:
Segment V . It is inanterior-inferior position, between the middle and right hepatic veins, wherethe blood drains from the parenchyma. It is vascularized by the right portalbranches.
VI段：它对应于右外侧或后下部。它从门静脉右外侧支接受血液，然后引流到肝右静脉。
原文:
Segment VI. It correspond tothe lower part of the lateral or posterior right sector. It receives blood fromthe right lateral branch of the portal vein and drains into the right hepaticvein.
VII段。位于第VI段上方，由门静脉右上外侧支供血，引流至肝右静脉。
原文:
Segment VII. Located abovesegment VI, it is supplied by lateral upper right branches of the portal veinand drains into the right hepatic vein.
VIII段位于第V段上方的前位，由内侧段静脉的上支供应，同时遵循第V段的引流方式
原文:
Segment VIII. It is inanterior position above segment V , supplied by upper branches of the vein ofthe medial sector, while it follows the drainage modalities of the segment V.
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