Right sectional portal veins originate independently from the common portal vein Portal vein divides into three branches: left portal vein, right anterior portal vein, and right posterior portal vein The overall incidence of portal vein variation is reported to be ~25% (range 20-30%), which should be recognized prior to procedures such as liver transplantation, complex hepatectomy and portal vein embolization 3,6-8: The inferior mesenteric vein joins the splenic vein 40% of the time, the superior mesenteric vein 40% of the time, and portomesenteric confluence at 20% of the time 3. When there is an obstruction in the portal vein or hepatic veins, portosystemic collateral pathways open to allow the drainage of excessive portal system blood into the systemic venous system 4. Sappey veins (left branch of the portal vein) 2,4 Gastric veins (behind the first part of the duodenum)Ĭystic veins (right branch of the portal vein) Inferior mesenteric vein (portomesenteric confluence) Posterior superior pancreaticoduodenal vein (through the posterior pancreaticoduodenal sulcus) TributariesĪlong its length, the portal vein receives various tributaries including: These vessels ultimately empty into the hepatic sinusoids to supply blood to the liver.ħ5% of the blood supplied to the liver comes from the portal vein, but it only supplies 50% of the oxygen supply to the liver. Each portal venule courses alongside a hepatic arteriole and the two vessels form the vascular components of the portal triad. The portal vein ramifies further, forming smaller venous branches and ultimately portal venules. The main branches of the left portal vein originate from the umbilical portion, and supply liver segments 2, 3 and 4 5. The left portal vein may be divided into transverse and umbilical portions, as delineated by the ligamentum venosum, and is mostly extrahepatic in its course. The right portal vein divides into anterior (supplying segments 5 and 8) and posterior (supplying segments 6 and 7) branches. Immediately before reaching the liver, the portal vein divides in the porta hepatis into left and right portal veins. The portal vein usually measures approximately 8 cm in length in adults with a maximum diameter of 13 mm 2. It originates posterior to the neck of the pancreas where it is classically formed by the union of the superior mesenteric and splenic veins (the portovenous/portomesenteric confluence) 3. The origin of the vein defines the location of the pancreatic neck.Īs it courses to the right towards the liver it inclines superiorly running in the free edge of the lesser omentum 4 ( hepatoduodenal ligament) with the other structures of the portal triad ( common hepatic duct and common hepatic artery) anterior to it 3. The portal vein is separated from the inferior vena cava by the epiploic foramen (of Winslow) 4. In addition to the hepatic portal venous system, there is also a hypophyseal portal system that passes blood from the hypothalamus to the anterior pituitary 1. TerminationĪt the lower third of thigh in its terminal fourth perforating branch.A portal venous system connects two capillary beds, meaning one organ / organ system will drain blood into another organ / organ system, before returning to the heart. Posterolateral aspect of the femoral artery at the upper part of the femoral triangle, 2-5 cm below the inguinal ligament CourseĪt first lateral to the femoral artery, it then runs behind it and the femoral vein to the medial side of the femur, and passes downward behind the adductor longus muscle, ending in a small terminal branch that pierces the adductor magnus muscle. termination: within the thigh as the terminal perforating artery (4 th perforating artery).
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