正常肝脏解剖

StephenW

Normal liver anatomy†

    Lena Sibulesky M.D.*

Article first published online: 29 MAR 2013

DOI: 10.1002/cld.124

The normal color of the liver is brown and the external surface is smooth (Fig. 1). The liver is about 2% of body weight in the adult, which amounts to approximately 1400 g in females and 1800 g in males. The liver receives its blood supply from two sources: 80% is delivered by the portal vein, which drains the spleen and intestines; the remaining 20%, the oxygenated blood, is delivered by the hepatic artery. The portal vein is formed by the union of the splenic and the superior mesenteric veins with the inferior mesenteric vein draining into the splenic vein (Fig. 2). In the majority of cases, the common hepatic artery is a branch of the celiac artery along with the splenic and left gastric arteries (Figs. 3 and 4). Occasionally, the hepatic artery has accessory or replaced vessels supplying the liver. The accessory or replaced right hepatic artery is a branch of the proximal superior mesenteric artery, while the accessory or replaced left hepatic artery is a branch of the left gastric artery (Fig. 3). Multiple anatomic variations, however, may also exist in the anatomy of the hepatic artery.1

Figure 1. Normal liver.


Figure 2. Portal venous drainage.


Figure 3. Arterial supply to liver and aberrant arterial anatomy.


Figure 4. Posterior view of the liver.


Externally, the liver is divided by the falciform ligament into a larger right lobe and a smaller left lobe (Fig. 5). The falciform ligament attaches the liver to the anterior abdominal wall. Its base contains the ligamentum teres, which has a remnant of the vestigial umbilical vein. In cirrhosis, this vein recanalizes as a result of portal hypertension.

Figure 5. Morphological anatomy of the liver.


Based on Couinaud classification, the liver is divided into eight independent functional segments (Figs. 6 and 7). Each segment has its own portal pedicle consisting of the hepatic arterial branch, portal branch, and the bile duct with a separate hepatic venous branch that provides outflow (Fig. 8). The numbering of segments is in a clockwise manner. Segments II and III, which are known as the anterior and posterior segments of the left lobe, respectively, are also known collectively as the left lateral segment of the liver and the topographic left lobe. Segment IV is the medial segment of the left lobe. Segments II, III, and IV collectively make up the functional left lobe of the liver. The functional right lobe of the liver is made up of segments V and VIII, the anterior segments, and segments VI and VII, the posterior segments. Segment I, the caudate lobe, is located posteriorly.

Figure 6. Functional anatomy of the liver.


Figure 7. Posterior view of the liver.


Figure 8. Segmental anatomy of the liver.


The outflow of the liver is provided by the three hepatic veins. The right hepatic vein divides the right lobe of the liver into anterior and posterior segments. The middle hepatic vein divides the liver into the right and left lobes and runs in the same plane with the inferior vena cava and the gallbladder fossa. The left hepatic vein divides the left liver into medial and lateral segments. The portal vein divides the liver into the upper and lower segments (Fig. 8).

The segmental liver anatomy is important to radiologists and surgeons, especially in view of the need for an accurate preoperative localization of focal hepatic lesions.2, 3 Liver resection depends on accurate localization of the hepatic lesions and knowledge of liver anatomy. Liver resection is now practiced widely with reduced morbidity and minimal mortality. Nonanatomic resections encompass wedge resections. Segmentectomies are anatomical resections of segments based on Couinaud classification. Bisegmentectomy includes resection of segments II and III is known as a left lateral segmentectomy. Resection of segment IV is known as a left medial segmentectomy, resection of segments V and VIII is known as a right anterior segmentectomy, and resection of segments VI and VII are known as a right posterior segmentectomy. Resection of segments II, III, and IV is known as the left lobe resection or left hepatectomy. Resection of segments V, VI, VII, VIII is known as right lobe resection or right hepatectomy. Extended right hepatectomy includes segments IV to VIII, while extended left hepatectomy includes segments II, III, IV, V, VIII (Table 1).

Table 1. Hepatic Anatomy and Resection Nomenclature

Anatomical Resections

Liver Segments

Left lateral segmentectomy

II, III

Left medial segmentectomy

IV

Right anterior segmentectomy

V, VIII

Right posterior segmentectomy

VI, VII

Left hepatectomy

II, III, IV

Right hepatectomy

V, VI, VII, VIII

Extended left hepatectomy

II, III, IV, V, VIII

Extended right hepatectomy

IV, V, VI, VII, VIII

Cirrhosis is an end result of parenchymal degeneration, regeneration, and scarring (Fig. 9). The cirrhotic liver varies in color, size, and appearance, depending on etiology. It might be large and green in diseases with biliary obstruction, such as primary sclerosing cholangitis or yellow and small in advanced alcoholic cirrhosis. It is firm and appears either micro- or macronodular as a result of formation of regenerative nodules with surrounding fibrosis in the parenchyma of the liver. Portal hypertension develops because of liver stiffness and increased resistance to flow. As a result, the blood is shunted away from the liver, and new thin dilated vessels form, shunting the blood away from the portal to the systemic circulation. Examples include esophageal, gastric, and rectal varices.4

Figure 9. Liver cirrhosis.



Acknowledgements
I thank Raouf E. Nakhleh for revising the paper and Margaret A. McKinney and David T. Smyrk for creating the figures.

StephenW

肝脏的正常颜色是棕色和外部表面是光滑的（图1） 。肝脏是约2％体重的成年人，这相当于在女性约1400克和1800克的男性。肝脏接收其血液供应来自两个方面： 80 ％是由门静脉，这牵扯了脾脏和肠道交付，其余的20 ％ ，含氧的血液，是由肝动脉交付。门静脉由脾和肠系膜上静脉与肠系膜下静脉引流入脾静脉（图2）联合组成。在大多数情况下，常见的肝动脉是腹腔动脉连同脾和胃左动脉（图3和4）的一个分支。偶尔，肝动脉具有附件或替换容器供给肝脏。配件或更换肝右动脉近端肠系膜上动脉的一个分支，而该配件或更换左肝动脉是胃左动脉（图3）的一个分支。多个解剖变异，但是，也可能存在于肝artery.1的解剖结构
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图1。正常肝脏。
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图2。门静脉回流。
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图3。动脉供应肝脏和动脉异常解剖。
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图4。后视图肝脏。

从外部看，肝脏是由镰状韧带分成较大右叶和较小的左叶（图5） 。镰状韧带附着肝脏前腹壁。其基本包含了肝圆韧带，里面有残留脐静脉的遗迹。在肝硬化，这一脉recanalizes为门脉高压所致。
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图5。肝脏形态解剖。

根据奎诺分类，肝分为八个独立的功能段（图6和7）。每个段都有自己的门蒂由肝动脉分支，门静脉分支和胆管有一个单独的肝静脉分支，它提供流出（图8） 。段的编号是沿顺时针方式。段II和III ，其被称为左叶的前段和后段，分别也被统称为肝脏和地形左叶的左侧部分。段四是内侧段左叶。段II，III ，和IV共同组成肝脏的功能左叶。肝功能右叶是由段Ⅴ和Ⅷ前段和段第六和第七，后段。段我，尾状叶，位于后方。
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图6。肝脏的功能解剖。
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图7。后视图肝脏。
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图8。肝脏解剖分段。

肝脏的流出是由三个肝静脉提供。肝右静脉将肝脏分成前段和后段的右叶。肝中静脉将肝脏分成与所述下腔静脉和胆囊窝同一平面的右侧和左侧肺叶并运行。左肝静脉分肝左成内侧和外侧段。门静脉将肝脏分成上段和下段（图8） 。

节段性肝解剖是非常重要的放射科医生和外科医生，尤其是考虑到需要肝脏局灶性lesions.2准确的术前定位， 3肝切除取决于肝脏病变肝脏解剖和知识的准确定位。肝切除术是目前广泛实行降低发病率和死亡率最低。 Nonanatomic切除包括楔形切除术。 Segmentectomies是分部的基础上奎诺分类解剖切除。 Bisegmentectomy包括切除区段II和III被称为左外侧段切除的。的Ⅳ段切除术被称为左内侧段切除，切除部分V和VIII被称为右前段切除，并切除部分第六和第七的是被称为右后段切除。段II的切除， III和IV是被称为左叶切除或左肝叶切除。段五，六，七切除术，八，被称为右叶切除或右半肝切除术。扩大右半肝切除，包括部分四到八，而扩展的左半肝切除包括段Ⅱ，Ⅲ ，Ⅳ， Ⅴ，Ⅷ （表1） 。
表1中。肝脏解剖和切除NomenclatureAnatomical切除术肝段
左外侧段切除Ⅱ，Ⅲ
左内侧段切除四
右前段切除Ⅴ，Ⅷ
右后段切除六，七
左半肝切除II，III， IV
右半肝切除术五，六，七，八
扩大左半肝切除Ⅱ，Ⅲ ，Ⅳ， Ⅴ，Ⅷ
扩大右半肝切除术IV ，V，VI ， VII，VIII

肝硬化是肝实质变性，再生和瘢痕形成（图9）的端结果。的肝硬化的颜色，大小和外观的变化取决于病因。这可能是大和绿色与胆道梗阻，如原发性硬化性胆管炎或黄小中晚期酒精性肝硬化的疾病。它是坚定的，要么会出现微量或为大结节形成再生结节与肝脏实质周围纤维化所致。门静脉高压症的发展，因为肝脏硬度，增加流动阻力。其结果是，血液被分流远离肝脏，新薄扩张血管形成，分流的血液远离入口到体循环中。实例包括食管，胃和直肠varices.4
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图9。肝硬化。
致谢

我感谢拉乌夫E. Nakhleh为修改的文件和Margaret A.麦金尼和David T. Smyrk创建的数字。