Chapter 12 Liver

• Liver Anatomy


  • Occupies the major portion of the right hypochondrium
  • Extends inferiorly into the epigastrium and laterally into the left hypochondrium
• Liver Anatomy


  • Superiorly, it reaches the dome of the diaphragm
  • Posteriorly, it borders the bony region of the posterior abdominal wall
  • Bulk of the liver lies beneath the right costal margin
  • Anterosuperior surface of the liver fits snugly into the dome of the diaphragm
  • Separated from overlying pleural cavities and pericardium
• Liver Anatomy


  • Enclosed by a fibrous capsule known as Glisson's capsule
  • A portion of the posterior surface of the liver is without a peritoneal covering and is called the bare area
• Liver Division by Hepatic Veins


  The liver is divided into the left, right, and caudate lobes
• Liver Division


  • The Liver is divided into 3 lobes: a right, a left and a caudate lobe (Quadrate = Sonographically is the medial segment of left)
  • The right and left lobes are subdivided into 4 segments: Anterior and posterior on the Rt and lateral and medial on the left
• Couinaud's Liver Segmentation


  • The pattern of anatomic segmentation provides the basis for surgical resections of the liver
  • Couinaud's liver segmentation is based on venous anatomy, with either hepatic or portal veins dividing the liver
• Couinaud's Liver Segmentation


  1. The Right hepatic vein divides the R lobe into anterior and posterior segments

  2. The middle hepatic vein divides the liver into the R and L lobes

  3. The falciform Ligament divides the left lobe into medial and lateral segments

  4. The portal vein divides the liver into upper and lower segments
• Liver: Left Lobe


  • Left lobe is more varied in size
  • Left intersegmental fissure divides medial and lateral segments along with left hepatic vein
  • Falciform ligament and ligamentum teres are located within this fissure
• Liver: Right Lobe


  • 6× larger than left lobe
  • Right intersegmental fissure divides anterior and posterior segments along with right hepatic vein
• Liver: Caudate Lobe


  • Smallest lobe
  • Separated from the left hepatic lobe by the proximal portion of the left hepatic vein and the fissure for the ligamentum venosum
• Liver Vasculature: Hepatic Veins


  • Increase in size as they drain toward the diaphragm
  • Triphasic hepatofugal blood flow
  • Indistinct, anechoic borders
• Liver Vasculature: Proper Hepatic Artery


  • Divides into right and left hepatic arteries
  • Cystic artery is a branch of the right hepatic artery
  • Low-resistance blood flow
• Liver Vasculature: Portal Veins


  • Decrease in size as they approach the diaphragm
  • Continuous, monophasic hepatopetal blood flow
  • Echogenic walls due to thick collagenous tissue in the walls
• Liver Vasculature


  1. The MPV enters the porta hepatis of the liver and divides into Rt and Lt branches

  2. These veins then branch into medial and lateral segments on the left and anterior and posterior segments on the right
• Liver Vasculature


  • The MPV branches into the R and L portal vein once it enters the liver
  • The MPV can be seen entering the liver at the porta hepatis
• Liver Vasculature


  • The MPV carries nutrient rich blood into the liver. Blood flow into the liver via the MPV is termed hepatopedal flow.
  • In some cases of liver pathology, the blood flow in MPV may become reversed due to increased resistance into the liver. (portal hypertension). Reversed blood flow into the liver via the MPV is termed hepatofugal flow.
• Liver Sonographic Landmarks: Main Lobar Fissure


  • Appears as an echogenic line connecting the neck of the gallbladder and the portal vein
  • Helpful when trying to locate the gallbladder
• Liver Sonographic Landmarks: Falciform Ligament


  • Sonographically divides the left lobe of the liver into medial and lateral segments
  • Contains the ligamentum teres
  • Connects the liver to the anterior abdominal wall and to the diaphragm
• Liver Sonographic Landmarks: Ligamentum Teres


  • The obliterated fetal portion of the umbilical vein
  • It appears as a bright echogenic focus and is seen as the rounded termination of the falciform ligament
• Peritoneal Spaces: Right Subphrenic Space


  Located inferior to the diaphragm and superior to the liver
• Peritoneal Spaces: Subhepatic Space


  • Located posterior and inferior to the liver
  • Forms part of Morison's pouch
• Peritoneal Spaces: Morison's Pouch (Hepatorenal Space)


  • Separates the liver from the Right kidney
  • It is the posterior, superior extension of the subhepatic space
• Peritoneal Divisions


  • Greater sac (Abdominal cavity) - Encloses most of the abdominal organs; enclosed organs called "intraperitoneal"
  • Lesser sac (Omental bursa) - Small sac bordered anteriorly by the stomach, posteriorly by the pancreas and a portion of the transverse colon
  • Epiploic of Winslow (Omental foramen, epiploic foramen) - Passageway between greater and lesser sacs just inferior to the liver
  • Lesser omentum (Gastrohepatic omentum, small omentum) - Double peritoneum extends from liver to lesser curvature of stomach and beginning of duodenum
  • Greater omentum (Gastrocolic omentum) - Large fold of peritoneum that extends from stomach, passes anteriorly to the colon and small intestine
• Normal Size of the Adult Liver


  • Weight: Males: 1400-1800 g
  • Right Lobe Midclavicular: 13-17 cm
  • Left Lobe: Highly variable
• Physiology


  The liver is a primary center of metabolism, supporting multiple body systems and activities. In support of digestive and excretory systems, the liver metabolizes fats, carbohydrates, and proteins and forms bile and urea
• Functions of the Liver


  • Metabolic functions of the liver involve uptake of body nutrients, such as carbohydrates, amino acids, or proteins, fats, and vitamins
  • Liver serves as a storage site for these substances, performs metabolic conversions of these substances into nutrients, and subsequently releases them into blood and bile vessels
• Functions of the Liver


  • Stores vitamins and other metabolic substances
  • Reservoir for blood that is released as it regulates blood volume and blood flow through the body
  • Serves as a major source of body heat as a result of the many hepatocellular chemical reactions that take place within it
• Sonographic Appearance of the Normal Liver


  • Homogeneous and moderately echogenic
  • Minimally hyperechoic to isoechoic to normal renal cortex
  • Bile ducts appear as avascular anechoic tubular structures
• Normal Variants


  • Distal papillary process of caudate lobe - This process appears as a rounded prominence on the anteroinferior aspect of the caudate, may be confused with enlarged lymph node or another extrahepatic lesion
  • Elongated left lobe - Extension of the left lobe laterally, may extend all the way to the spleen
  • Reidel's lobe - Tonguelike inferior extension of the right lobe, as far caudally as the iliac crest, identified when liver tissue extends well below the inferior pole of the right kidney during normal respiration