Liver

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1. By. Dr Vibhash Kumar Vaidya Department of Anatomy LIVER

2. Introduction (Greek hepar : liver) It is the largest gland of the body. occupying much of the right upper part of the abdominal cavity . It consists of both exocrine and endocrine parts. The liver performs a wide range of metabolic activities necessary for homeostasis, nutrition, and immune response.

3. M ain functions are It secretes bile and stores glycogen. It synthesizes the serum proteins and lipids. It detoxifies blood from endogenous and exogenous substances (e.g., toxins, drugs, alcohol, etc.) that enter the circulation. It produces hemopoietic cells of all types during fetal life .

4. LOCATION The liver almost fully occupies: T he right hypochondrium. U pper part of the epigastrium. A nd part of the left hypochondrium up to the left lateral (midclavicular) line. It extends upward under the rib cage as far as the 5th rib anteriorly on the right side ( below the right nipple) and left 5th intercostal space The sharp inferior border crosses the midline at the level of trans pyloric plane (at the level of L1 vertebra .

5. SHAPE, SIZE, AND COLOUR Shape The liver is wedge shaped and resembles a four-sided pyramid laid on one side with its base directed towards the right and apex directed towards the left . Colour It is red-brown in colour . Weight In males: 1.4 to 1.8kg. In females: 1.2 to 1.4kg. In newborn: 1/18th of the body weight. At birth: 150 g. Proportional weight: In adult 1/40th of the body weight.

6. EXTERNAL FEATURES The wedge-shaped liver presents: T wo well-defined surfaces: diaphragmatic and visceral. O ne well-defined border: inferior border .

7. Diaphragmatic Surface The dome-shaped diaphragmatic surface includes smooth peritoneal areas which face superiorly, anteriorly and to the right. And a rough bare area (devoid of the peritoneum) which faces posteriorly . The inferior vena cava (IVC) is embedded in the deep sulcus in the left part of the bare area. In most cases, this sulcus is roofed by the fibrous tissue termed ligament of IVC which may contain hepatic tissue converting the sulcus into the tunnel. The peritoneal ligaments are coronary, left and right triangular and falciform ligaments .

8. Visceral Surface (Inferior Surface ): R elatively flat or concave. It is directed downward , backward, and to the left. It is separated in front from the diaphragmatic surface by the sharp inferior border and behind from the diaphragm by the posterior layer of coronary ligament. The notable features on the visceral surface are: Fossa for the gallbladder. Fissure for the ligamentum teres hepatis. Porta hepatis. The visceral surface is covered by the peritoneum except at the fossa for gallbladder and the porta hepatis .

9. Inferior Border The features of the inferior border are as follows: It separates the diaphragmatic surface from the visceral surface . It is rounded laterally where it separates the right lateral surface from the inferior surface. It is thin and sharp medially where it separates the anterior surface from the inferior surface. It presents two notches: (a) Notch for ligamentum teres or interlobar notch: It is located just to the right of the median plane. (b) Cystic notch: It is located about 5 cm to the right of the median plane and often corresponds to the fundus of the gallbladder .

10. LOBES OF THE LIVER Anatomical Lobes: On the diaphragmatic surface: the liver is divided into two lobes , right and left, by the attachment of the falciform ligament. The right lobe which forms the base of the wedge-shaped liver is approximately six times larger than the left lobe .

11. On the visceral surface: the liver is divided into four lobes : Right lobe: to right of the fossa for gallbladder. Left lobe: to the left of the fissures for ligamentum teres and ligamentum venosum. Quadrate lobe: between the fossa for gallbladder and the fissure for ligamentum teres below the porta hepatis . Caudate lobe: between the groove for IVC and the fissure for ligamentum venosum.

12. Physiological Lobes/Functional Lobes/True Lobes The division of the liver into lobes is based on the intrahepatic distribution of branches of the bile ducts, hepatic artery, and portal vein. The liver is divided into right and left physiological lobes by an imaginary sagittal plane/line ( Cantlie’s plane/line). On the posteroinferior surface: this plane passes through the fossa for gallbladder, to the groove for IVC. ( Note: Caudate lobe is equally shared between the right and left lobes .) The anterosuperior surface: this plane passes from the IVC to the cystic notch present a little to the right of the falciform ligament. The physiological right and left lobes are approximately equal in size .

13. HEPATIC SEGMENTS (SEGMENTS OF THE LIVER ) There are eight hepatic segments. They are deduced as follows The right physiological lobe is divided into anterior and posterior parts, and the left physiological lobe into medial and lateral parts. Each of these parts is further divided into upper and lower parts and form eight surgically resectable hepatic segments . The veins draining the hepatic segments are intersegmental , i.e., they drain more than one segments.

14. Couinaud’s segments: According to nomenclature of Couinaud , the hepatic segments are numbered I to VIII. I to IV in the left hemi liver and V to VIII in the right hemi liver. According to this nomenclature, the segment I corresponds to the caudate lobe and segment IV corresponds to the quadrate lobe. Segment I to IV of the left lobe are supplied by the left branch of hepatic artery, left branch of portal vein and drained by left hepatic duct. The segments V to VIII of right lobe are supplied by right hepatic artery, right branch of portal vein and drained by right hepatic duct.

15. PERITONEAL RELATIONS Most of the liver is covered by the peritoneum. The areas which are not covered by the peritoneum are: Bare area of the liver: It is a triangular area on the posterior aspect of the right lobe. Fossa for gallbladder, on the inferior surface of the liver between right and quadrate lobes. Groove for IVC, on the posterior surface of the right lobe of the liver. Groove for ligamentum venosum. Porta hepatis .

16. LIGAMENTS False Ligaments: are actually peritoneal folds and include: Falciform ligament. Coronary ligament. Right triangular ligament. Left triangular ligament. Lesser omentum . True Ligaments: are actually the remnants of fetal structures and include: Ligamentum teres hepatis. Ligamentum venosum .

17. RELATIONS Diaphragmatic Surface: Superior Surface:- The convex right and left parts of this surface fit into the corresponding domes of the diaphragm, which separate them from the corresponding lung and pleura. The central depressed area of this surface is related to the central tendon of the diaphragm, which separates it from the pericardium of the heart. Hence, this area is often termed cardiac impression . Anterior Surface:- X iphoid process and anterior abdominal wall in the median plane and diaphragm on each side. The falciform ligament is attached to this surface a little to the right of the median plane . Right Lateral Surface:- Diaphragm opposite 7th to 11th ribs in the midaxillary line .

18. Posterior Surface:- This surface presents: bare area of the liver, groove for IVC, caudate lobe, fissure for ligamentum venosum, and posterior surface of the left lobe. The bare area of the liver is a triangular area to the right of groove for the IVC between the two layers of coronary and right triangular ligaments. It is in direct contact with the diaphragm. The right suprarenal gland is related to the inferomedial part of this area, i.e., near the groove for IVC. The groove for IVC as the name indicates lodges the IVC. The caudate lobe is related to the superior recess of the lesser sac . E sophagus , just to the left of the upper part of fissure for ligamentum venosum and causes esophageal impression. The fundus of the stomach is related just to the left of the esophageal impression.

19. Visceral Surface (Inferior Surface):- The inferior surface of the left lobe is related to the stomach , which produces a gastric impression. Near the left side of the fissure for ligamentum venosum, this surface presents a slight elevation that comes in contact with the lesser omentum. Hence , it is called tuber omentale / omental tuberosity. The quadrate lobe is related to the pyloric end of the stomach and the first part of the duodenum. The fossa for gallbladder, occupied by the gallbladder with its cystic duct. The right colic flexure is related to the inferior surface to the right of the gallbladder colic impression. The junction of first and second parts of the duodenum is related to the right upper part of the fossa for gallbladder produces the duodenal impression. The right kidney is related to the inferior surface posterior to the colic impression and to the right of the duodenal impression and causes renal impression.

20. Relations of diaphragmatic and visceral surfaces of the liver.

21. BLOOD SUPPLY The liver is a highly vascular organ. It receives blood from two sources . The arterial blood (oxygenated) is supplied by the hepatic artery and venous blood (rich in nutrients) is supplied by the portal vein. T hrough the liver. About 80% of this is delivered through the portal vein and 20% is delivered through the hepatic artery .

22. VENOUS DRAINAGE Most of the venous blood from liver is drained by three large hepatic veins: left hepatic vein between medial and lateral segments of the left true lobe, middle hepatic vein between true right and left true lobes, right hepatic vein between anterior and posterior segments of the right true lobe .

23. NERVE SUPPLY The liver is supplied by both sympathetic and parasympathetic fibres. The sympathetic fibres are derived from the coeliac plexus. The parasympathetic fibres are derived from the hepatic branch of the anterior vagal trunk .

24. FACTORS KEEPING THE LIVER IN POSITION Hepatic veins connecting the liver to the IVC. Intra-abdominal pressure maintained by the tone of abdominal muscles. Peritoneal ligaments connecting the liver to the abdominal walls .

25. Clinical correlation Cirrhosis of the liver: The hepatocytes sometimes may undergo necross following their injury and death caused by infection , toxins, alcohol, and poisons. The dead hepatocytes are replaced by fibrous tissue by the proliferation of the perilobular connective tissue. The resultant hepatic fibrosis is clinically termed cirrhosis of the liver. The patient develops jaundice due to obstruction of bile flow .

26. Needle biopsy of the liver: In needle biopsy of the liver, the needle is inserted in the midaxillary line through 9th or 10th intercostal space. The needle passes through the chest wall,costodiaphragmatic recess of the pleura , diaphragm, and right anterior intraperitoneal space to enter the liver. Needle inserted above the 8th intercostal space will injure the lung.