LIVER Learning objectives At the end of the lecture the student should be able to: Define liver. Identify lobes and surfaces of liver. Identify the segments of liver. Liver Largest gland situated in right hypochondrium epigastric and left hypochondrium. It is held in position mainly by the continuity of hepatic veins with inferior vena cava. Also by general intra-abdominal pressure due to the tons of abdominal muscles. Liver 1.4 – 1.8kg (M) 1.2 – 1.4kg (F). Larger in fetus Wedge shaped, Reddish brown in colour. Firm in consistency. Highly vascular. HEPATIC LOBES It is divided into right and left lobes by the attachment of falciform ligament anteriorly and superiorly. Inferiorly – Fissure for ligament teres (oblitrated umblical vein). Posteriorly – Ligament venosum (Remanent of sinus venosus). Left lobe, Right lobe Left lobe Thin, flattened from and constitutes the having above to down wards 1/6th of total organ Anterior Posterior Superior Inferior surfaces Near the fissure of ligament venosum its inferior surfaces presents a rounded elevation known as omental omentale). tuberosity (tuber Right lobe Constitutes the 5/6th of the total organ. This lobe contributes in all the surface of liver and presents with caudate and quadrate lobes. Quadrate lobe, Caudate lobe Quadrate lobe: On the inferior surface it is bounded infront by inferior border of liver,On left by ligament teres, Posteriorly by portahepatis and on Right by fossa for gallbladder. Caudate lobe: On posterior surface Groove for inferior vena cava (right) fissure for ligament venosum (left) porta hepatis (inferior) Caudate lobe is connected to the right lobe of liver by the caudate process. A small rounded projection known as papillary process. Porta Hepatis This is a deep transverse fissure about 2” long at inferior surface of liver on its right lobe between the caudate and quadrate lobe below and infront. Portal vein, hepatic artery and hepatic plexus of nerves enter in liver through this fissure. While the right and left hepatic ducts and few lymphatics leave it (known as hilum of liver) Vein, artery, duct (VAD): Behind to forward relations of structures in porta hepatis. Bare areas of liver (where peritoneum is absent): On the posterior surface of right lobe limited above and below by two layers of coronary ligament. Groove for inferior vena cava, on the posterior surface. Fossa for gallbladder on inferior surface of right lobe. Porta hepatis Along the lines of reflection of peritoneum. PERITONEAL REFLECTIONS Falciform ligament: This is a sickle shaped fold of peritoneum which ascends from umbilicus to liver and connects the anteroposterior surface of liver to the anterior abdominal wall and to the under surface of diaphragm. Its free margin contains ligament teres and small paraumbilical veins (ligamentum teres is a ramanent of umbilical vein). At its upper end the two layers of falciform ligament are separated. Falciform ligament Left layer is continuous with anterior layer of the left triangle ligament. Right layer is continuous with the upper layer of coronary ligament. Coronary ligament: It is a reflection of peritoneum from diaphragm to superior and posterior surfaces of right lobe of liver. It consists of an upper and lower layers which are continuous at their extremities with the right triangular ligament of liver but diverging to the left as to enclose posteriorly a large triangular area on the right lobe of liver (Bare area). Right and left triangular ligament Lower layer is continuous with posterior layer of right triangular ligament and goes to posterior surface of right lobe. Left triangular ligament: Connects the superior surface of left lobe of liver to diaphragm. Right triangular ligament: Connects the lateral part of posterior surface of right lobe of liver to diaphragm. Lesser omentum: From portahepatis to lesser curvature of stomach . HEPATIC SURFACES Superior surface: Fits under the diaphragm. Covered by diaphragm except over a small triangular area where two layers of upper part of falciform ligament diverge. Central part shows cardiac impression. Also related to diaphragmatic pleura of right side and right lung and to pericardium and ventricular part of heart and to smaller extent to diaphragmatic pleura of left side and base of left lung HEPATIC SURFACES Anterior surface: Triangular in shape Whole covered with peritoneum except the line of attachment of facliform ligament. It is in contact with diaphragm which separates it on right side from pleura and 6th – 10th ribs with their costal cartilages and on the left side 7 – 8 C. cartilage. The median part of anterior surface of liver lies behind the xiphoid process of sternum. Right surface is covered with peritoneum and is related to right portion of diaphragm which separates it from right lung, pleura and 7 – 11 ribs. The upper 1/3rd is related to diaphragm and the pleura of right lung. The middle 1/3rd diaphragm and costodiaphragmatic recess. The lower 1/3rd diaphragm. HEPATIC SURFACES Posterior surface: This is wide and convex on right but narrow on the left. Its middle part shows a deep concavity for the vertebral column. Bare area: Above – superior and inferior layers of coronary ligament. Base – Groove for inferior vena cava. Apex – Right triangular ligament. Groove for inferior vena cava Lodges the upper part of inferior vena cava and being pierced by hepatic veins. Lateral to lower end of groove, the bore area lodges the upper part of right supra renal gland (supra renal impression). Caudate lobe occupies the rest of posterior surface of the right to be liver. It is related to crura of diaphragm, right phrenic artery and coelic trunk. HEPATIC SURFACES The fissure for ligament venosus is very deep and extends to the front of caudate lobe. Ligament venosum is a remnant of ductus venosus of foetal life. The posterior surface of left lobe is marked by oesophageal impression. Inferior surface (visceral surface) • It is quardilateral and is directed downward, backward and left. On the inferior surface of left lobe: There is large concave gastric impression. • • It also bears the raised area which is in contact with lesser omentum i.e. omental tuberosity. Fissure of ligament teres (obliterated left umbilical vein) passes from the inferior border of liver to the left end of portahepatis. Inferior surface (visceral surface) • • • • Quadrate to be is related to lesser omentum, pylorus and 1st part of duodenum. When the stomach is empty the quadrate is related to 1st part of duodenum and to a part of Tr. Colon. There is a fossa for gallbladder. To the right of fossa of gallbladder the inferior surface of right to be bears the colic impression for the hepatic flexure of colon. Renal impression for right kidney and duodenal impression for 2nd part of duodenum. Segments of liver On the basis of blood supply and biliary drainage, the liver is divided into right and left functional lobes by a plane passing on the anterio-superior surfaces along the line joining the cystic notch to the groove for inferior vena cava. On the inferior surface the plane passes through the fossa of gallbladder. Segments of liver On the posterior surface it passes through the middle of caudate lobe. Right lobe – divide in to right anterior & right posterior. Left lobe – divide in to left anterior & left posterior. They are again divided into upper and lower parts. Blood supply of liver It receives 20% blood through Hepatic artery (coelic trunk) and 80% through the portal vein. Before entering into liver both hepatic artery and portal vein divide into right and left branches. Within the liver they redivide to form segmental vessels and further divide to form interlobular branches and then open in hepatic sinusoids. Veins of liver Veins: Sinusoids drain into interlobular veins which join to form sublobular veins which join together to form hepatic veins which open into inferior vena cava (portal vein also breaks up into sinusoids). Hepatic veins are arranged into upper and lower groups. Lymphatic drainage: Superfecial lymphatics run on the surfaces below the peritoneum and terminate into caval, hepatic, pericardial and coelic lymph nodes. Some lymph vessels from coronary ligament directly join the thoracic duct. Deep lymphatics end partly in nodes around inferior vena cava and in hepatic nodes. Nerve supply: Hepatic plexus is having sympathetic and parasympathetic fibers (vagus). Nerves through peritoneal ligaments. References Gray’s textbook of anatomy.