Bề mặt sau và kém là bất thường và biên giới rất nhiều cấu trúc khác intrabdominal. Gan là đôi khi được mô tả như có bốn thùy: phải, trái, vuông, và có đuôi. Đối với quy hoạch phẫu thuật, một mô tả giải phẫu phân đoạn được sử dụng dựa trên các phân đoạn biên giới với các chi nhánh tĩnh mạch cửa chính và ba tĩnh mạch gan chính. | The abdomen dominic blunt to ribs and costal cartilages. The posterior and inferior surface is irregular and borders numerous other intrabdominal structures. The liver is sometimes described as containing four lobes right left quadrate and caudate. For planning surgery a segmental anatomical description is used based on segments bordered by the main portal vein branches and the three main hepatic veins. This seems initially complex but less so once the plains of this division are appreciated. Key to the liver anatomy is the fact that it has a dual blood supply arterial blood accounts for around 10 to 20 of its blood supply and the portal vein providing the rest. This vein carries nutrient-rich blood from the gut and is much larger than the hepatic artery. The artery and portal vein branches run with the bile ducts taking bile in the opposite direction towards the duodenum. The hepatic veins drain directly into the inferior vena cava Fig. . Usually there are three main veins right middle and left entering the vena cava immediately below the diaphragm close to the right atrium and a smaller one draining only segment 1 caudate . In conditions restricting flow of blood through the portal circulation including cirrhosis of the liver portal venous blood may enter the systemic circulation via collateral vessels which enlarge. These are commonly seen in the lower esophagus as varices or within the anterior abdominal wall where these can be visible around the umbilicus. Such portosystemic anastomoses may also be seen in the anal canal and around the hilum of the spleen and left kidney. The smooth anterior surface is related to the inner aspect of ribs and costal margins the inferior posterior surface is related to the esophagus and stomach on the left and on the right to the gall bladder the second part of the duodenum the hepatic flexure of the colon and the right kidney and adrenal gland. The site where the artery and portal vein enter the liver and the common .
