Anatomy of Liver - Bare Area

The Liver

• The liver is the largest gland in the body, weighing approximately 1500g (2.5% of adult body weight)
• It lies mainly in the right hypochondrium and epigastrium, extending into the left hypochondrium
• The liver is protected by the thoracic cage and diaphragm, with its greater part lying deep to ribs 7-11 on the right side and crossing the midline towards the left below the nipple

Surfaces of the Liver

• The liver has two surfaces: a convex diaphragmatic surface (anterosuperior) and a relatively flat or even concave visceral surface (postero-inferior)
• The diaphragmatic surface is smooth and molded to the undersurface of the domes of the diaphragm, which separates it from the pleurae, lungs, pericardium, and heart
• The visceral surface is related to abdominal viscera, covered with peritoneum except at the fossa for the gallbladder, porta hepatis, and IVC groove

Bare Area of the Liver

• The bare area is triangular, inferior, and on the posterior surface of the right lobe, where there is no intervening peritoneum between the liver and the diaphragm
• The boundaries of the bare area are:
  • Anterior: superior layer of coronary ligament
  • Posterior: inferior layer of coronary ligament
  • Laterally: right and left triangular ligaments

Relations of the Liver

• Anterior: diaphragm, right and left pleura, lower margins of both lungs, right and left costal margins, xiphoid process, and anterior abdominal wall in the subcostal angle
• Posterior: diaphragm, right kidney, hepatic flexure of the colon, duodenum, gallbladder, inferior vena cava, esophagus, and fundus of the stomach

Fissures of the Liver

• Two sagittally oriented fissures, linked centrally by the transverse porta hepatis, form the letter H on the visceral surface
• The left fissure is the continuous groove formed:
  • Anteriorly by the fissure for the round ligament (lig.teres)
  • Posteriorly by the fissure for the ligamentum venosum
• The right fissure is the continuous groove formed:
  • Anteriorly by the fossa for the gallbladder
  • Posteriorly by the groove for the inferior vena cava

Porta Hepatis (Hilum of the Liver)

• A transverse fissure found on the posteroinferior surface between the caudate and quadrate lobes
• Structures passing through the porta hepatis include:
  • Right and left hepatic ducts
  • Right and left branches of the hepatic artery
  • Right and left branches of the portal vein

Blood Circulation through the Liver

• The blood vessels conveying blood to the liver are the hepatic artery (30%) and portal vein (70%)
• The hepatic artery brings oxygenated blood to the liver
• The portal vein brings venous blood rich in the products of digestion, which have been absorbed from the gastrointestinal tract to the liver
• The hepatic veins, which are intersegmental in their distribution and function, drain parts of adjacent segments

The Spleen

• Completely surrounded by peritoneum, except at the hilum where its margins give attachment to:
  • Gastrosplenic ligament to the greater curvature of stomach (carrying the short gastric and left gastroepiploic vessels)
  • Lienorenal (splenorenal) ligament to the left kidney (carrying the splenic vessels and the tail of pancreas)

Relations of the Spleen

• Anteriorly: stomach, tail of pancreas, left colic flexure, and left kidney
• Posteriorly: diaphragm, which separates it from the left pleura (left costo-diaphragmatic recess), left lung, and 9, 10, and 11 ribs
• Inferiorly: left colic flexure
• Medially: left kidney

Arterial Supply of the Spleen

• Splenic artery, the largest branch of the celiac artery
• Runs a tortuous course along the upper border of the pancreas
• Passes within the lienorenal ligament
• Divides into 4-5 terminal branches, which enter the spleen at the hilus
• The lack of anastomosis of these arterial vessels within the spleen results in the formation of vascular segments of the spleen with relatively avascular planes between them, enabling subtotal splenectomy