LIVER

• Largest gland of the body.

• Situated: In right upper border quadrant of abdominal cavity.

• Occupies whole of the right hypochondrium, greater part of epigastrium with extension into left hypochondrium.

• Weight: 

– 1500-1600 gm- males  

– 1200-1300 gm- females

• Liver is covered by Glisson’s capsule.

• Interior of liver is divided into hexagonal lobules.

• Lobule contains sinusoids have fenesterated endothelium covering the subendothelial space of Disse. 

Important cells in liver: 

• Hepatocytes (Parenchymal cells)

• Kupffer cells (monocytic-macrophages).

LOBES OF LIVER

• Liver can be divided into right & left lobe anatomically & physiologically.

ANATOMICAL LOBES:

• Anatomically liver is divided into a large right lobe & a small left lobe.

Right lobe:

• Larger & forms five sixth of liver.

• Caudate lobe & quadrate lobe are parts of anatomical right lobe.

Left lobe– forms only one sixth of liver.

• Situated on posterior surface of right lobe.

Bounded:

– on right by groove for IVC,

– on left by fissure for ligamentum venosum

– inferiorly by porta hepatis (containing hepatic artery, portal vein, hepatic duct, bile duct, nerve plexus & lymphatics).

• Just behind the porta hepatis caudate lobe is connected to rest of right lobe by caudate process.

• There is a small rounded elevation to the left, called papillary process.

• Caudate lobe lies in superior recess of lesser sac & is related to crura of diaphragm, right inferior phrenic artery & coelic artery.

2) QUADRATE LOBE:

• Situated on the inferior surface & rectangular in shape.

Bounded:

• anteriorly by inferior border of liver

• posteriorly by porta hepatis

• on right side by fossa for gall bladder

• on left side by fissure for ligamentum teres

 PHYSIOLOGICAL LOBES:

• Physiological right & left lobes are equally divided by an imaginary line (cholecysto-vena caval line)  running from fossa for gall bladder to the groove for IVC.

• The physiological right & left lobes have separate biliary drainage & vascular supply

• They are supplied respectively by right & left branches of portal vein & hepatic artery & 

• Bile is conveyed by the corresponding hepatic ducts (bile ducts).

• Belongs physiologically to both right & left lobes

It receives blood from right & left hepatic arteries:

– right & left phrenic vein; &

– drains bile into both right & left hepatic duct.

SEGMENTAL ANATOMY OF THE LIVER

Based on the distribution of portal vein & hepatic vein, 

Couinaud divided each physiological (functional) lobe of liver into 4 segments each & hence liver is divided into 8 segments.

1. The physiological left lobe

• Composed of 4 segments designated I to IV

• Supplied by left branch of hepatic artery, left branch of portal vein

• Drained by left hepatic duct

2. The physiological right lobe

• consists of segment V, VI, VII & VIII

• supplied by right hepatic artery, right branch of portal vein

• drained by right hepatic duct.

 

• Segment I corresponds to caudate lobe

• Segment IV to quadrate lobe

• RIGHT LOBE is subdivided into anterior & posterior segment.

• LEFT LOBE into medial & lateral segments.

Thus the segments of liver are:

• Right anterior- V (Inferior),  VII (Superior)

• Right posterior– VI (Inferior),  VII (Superior)

• Left medial– IV (Quadrate lobe): divded into IV a (Superior)    IV b (Inferior)

• Left lateral– II (Superior),  III (Inferior)

• Caudate lobe (Segment I) is considered as posterior segment.

• Liver has dual blood supply

• Receives 20% of its blood supply through hepatic artery

• 80% through portal vein.

• Venous drainage: through hepatic veins into IVC.