Week 5_Chapter 9 (PT1) Liver Anat

Anatomy of the Liver

• Location:

  • Occupies the right hypochondrium, extends into the epigastric and left hypochondrium.

  • Lies inferior to the diaphragm, with ribs covering most of the right lobe and part of the left.

• Weight:

  • Normal adult liver weighs between 1200-1600 g (2.6-3.5 pounds).

Liver Surfaces

• Glisson's Capsule:

  • Thin, fibrous capsule surrounding the liver.

  • Covered by peritoneum except for the caudate lobe and the bare area on the posterior surface.

Impressions on Liver

• Costal impressions from ribs.

• Other impressions include:

  • Colic impression from the right hepatic flexure of colon.

  • Duodenal impression.

  • Renal impression.

  • Suprarenal impression.

  • Gastric impression.

  • Esophageal impression.

Lobes of the Liver

• Divided into four lobes:

  • Right lobe.

  • Left lobe.

  • Quadrate lobe (medial segment of the left lobe).

  • Caudate lobe.

• The vascular anatomy further divides the liver into functional segments.

Anatomical Structures

• Ligaments:

  • Falciform ligament separates left and right lobes.

  • Coronary ligament connects the liver to the diaphragm.

  • Left and right triangular ligaments define the lateral borders of the liver.

• Surface Features:

  • Ligamentum teres (round ligament) runs along the inferior margin.

  • Gallbladder located at the inferior surface of the liver.

Right Lobe Anatomy

• Lies in the right hypochondrium and is six times larger than the left lobe.

• Separated from the left lobe by the falciform ligament and the main lobar fissure.

• Contains the porta hepatis, gallbladder fossa, and IVC fossa.

Left Lobe Anatomy

• Located in the epigastric and left hypochondriac regions.

• Divided into medial and lateral segments by the left hepatic vein (LHV) and left portal vein (LPV).

• Contains the quadrate lobe and is variable in size.

Caudate Lobe

• Located at the posterior surface of the left lobe.

• Borders defined by:

  • Posterior: Inferior vena cava (IVC).

  • Anterior: Ligamentum venosum.

• Caudate Process:

  • A variant that may appear as a papillary projection toward the right lobe.

Vascular Anatomy

• Intersegmental Anatomy:

  • RHV divides the right lobe into anterior and posterior segments.

  • MHV separates right and left lobes.

• Couinaud’s System:

  • Divides liver into eight segments based on vasculature structure.

Ligaments and Fissures

• Key ligaments include:

  • Falciform ligament: attaches liver to the anterior abdominal wall.

  • Ligamentum venosum: remnant of the fetal ductus venosus.

  • Hepatoduodenal ligament connects liver with the duodenum, containing crucial vascular structures.

Hepatic Arteries

• Account for 20-30% of blood flow to the liver; arising from the celiac trunk.

• Portal Triad includes:

  • Main Portal Vein (MPV).

  • Hepatic Artery.

  • Common Bile Duct.

Hepatic & Portal Veins

• Portal Venous System:

  • Accounts for 70-80% of blood supply to the liver.

  • MPV bifurcates into right and left portal veins.

  • Blood flows into sinusoids and onto hepatic veins.

• Hepatic Venous System:

  • Drains blood into the inferior vena cava.

• Function of the Veins:

  • The portal veins carry nutrient-rich blood from the intestines to the liver.

  • Hepatic veins drain deoxygenated blood from the liver into the IVC.

Liver Physiology

• Liver Lobule:

  • Functional unit of the liver; consists of sinusoids, central veins, hepatocytes, and bile canaliculi.

• Primary Functions:

  • Digestion: bile formation and excretion.

  • Metabolism: carbohydrate, fat, and protein metabolism.

  • Storage: iron and certain vitamins.

  • Detoxification: detoxifies drugs and metabolites.

• Blood Reservoir: Vertebrates, the liver contains a significant volume of blood.

Hepatic Disease vs. Obstructive Disease

• Hepatic Disease: Issues arising in hepatocytes affecting liver function (e.g., hepatitis).

• Obstructive Disease: Blocked bile flow leading to liver dysfunction (e.g., gallstones).

Liver Function Tests**

• Consider key enzymes and parameters such as AST, ALT, ALP, total bilirubin, and prothrombin time (PT).

• Tests help identify liver dysfunction and guide treatment approaches.

Sonographic Evaluation of the Liver

• Preparation: NPO for 6-8 hours to reduce bowel gas.

• Patient Position: Supine, left lateral decubitus, or prone.

• Transducer: 2.5 to 4 MHz for deeper imaging; assess echotexture and vascular structures.

• Assessment Criteria:

  • Measure liver size, evaluate echogenicity, and identify structural features.