THE LIVER

DEVELOPMENT: Foregut closely associated with primitive cystic and pancreatic ducts.

• Starts out as the hepatic diverticulum.
• Hepatic Duct elongates throughout development and joins with cystic duct to form common bile duct in the adult.
• The liver elongates into the septum transversum during development.
• It continues to grow into the diaphragm later, to create the bare area of the liver -- the part that has no peritoneum covering it.
• The omental foramen is a free border of the lesser omentum. The portal triad travels through this hole.
• The ventral mesentery in the embryo reduces to become the falciform ligament i the adult.
  

PRENATAL CIRCULATION: The liver is basically bypassed.

• Ductus Venosus: In the embryo, it connects the umbilical vein with the hepatic vein and inferior vena cava. It shunts blood going through the liver so that it really doesn't perfuse the liver, but rather bypasses right to the Inferior vena cava.
• Blood going through much of the embryonic portal vein system is shunted through the ductus venosus.
• After birth, the ductus venosus closes and its remnants become the ligamentum venosum, the ligament on the inferior, posterior aspect of the liver.
• The Round Ligament is what remains of the umbilical vein. It hangs down fro the falciform ligament.
  

LOCATION:

• The liver is not covered in the area of the falciform ligament attachment.
• Highest point is the right lobe. It rises to the 5th intercostal space.
  

EXTERNAL MORPHOLOGY:

• Ligaments:
• Coronary Ligament: Reflection of peritoneum off the posterior surface of the liver, with the diaphragm.
• A bare area is created by the reflection of the coronary ligaments on the diaphragm. The bare area touches the diaphragm.
• Right and Left Triangular Ligaments: Part of the Coronary Ligament. Formed by the two layers of peritoneum extending laterally.
• Falciform Ligament: Liver's reflection of peritoneum with anterior wall. The primitive ventral mesentery.
• Round Ligament (Ligamentum Teres Hepatis) hangs down from the falciform ligament, on the anterior side.
• Ligamentum Venosum: Posterior side of liver, separating the two lobes. It continues superiorly (on the posterior side) all the way to the superior margin of the liver.
• Lobes: The two lobes are separated by the falciform ligament.
• Left and Right Lobes: The functional lobes of the liver, demarcated by an imaginary line going between the inferior vena cava (superior part) and the gall bladder (inferior part).
• The right lobe is the larger lobe, extending superiorly to the fifth ICS when supine.
• The left lobe is the smaller lobe.
• Caudate and Quadrate Lobes: Both on the posterior side, surrounding the porta hepatis (i.e. portal triad).
• Caudate Lobe is directly superior to the porta hepatis. Part of the functional left lobe of the liver.
• It is closest to the vena cava.
• Quadrate lobe is directly inferior to the porta hepatis, also part of the left lobe of the liver.
• It is closest to the gall bladder.
• Peritoneal Reflections
• Subphrenic Recess: Recess created by coronary ligament reflecting off the diaphragm.
• Hepatorenal Recess: Recess between the right lobe of the liver and right kidney.
• Surfaces:
• Diaphragmatic Surface: The surface of the liver facing the diaphragm. Smooth.
• Visceral Surface: The posterior and left surfaces facing the stomach, duodenum, gall bladder, and pancreas.
  

INTERNAL MORPHOLOGY:

• Porta Hepatis: The hole going through the posterior side of the right lobe, containing the portal triad of vessels:
• Portal Vein
• Common Bile Duct
• Proper Hepatic Artery.
• Difference between functional (surgical) and anatomical lobes: anatomic lobes are divided by the falciform ligament.
• Functional lobes (as above) are divided by the imaginary line between the gall bladder and IVC.
• Each functional lobe is supplied by different vessels.

RELATIONSHIPS:

• Inferior Vena Cava: Goes over the reflection of the coronary ligament, through the bare area, on the superior posterior aspect of the liver.

CLINICAL CONSIDERATIONS:

• Subphrenic Recess: Air can collect in there as a result of surgeries.
• Hepatorenal Recess: This is the lowest area for fluid to collect in the upper abdominal cavity, when the patient is in supine position.

Category: Anatomy Notes