Fissure for round ligament

The fissure for the round ligament (fossa ligamenti teretis hepatis) is a shallow groove found on the visceral surface of the liver in domestic animals. It is an anatomical feature that serves as the passage for the round ligament of the liver (ligamentum teres hepatis), a fibrous remnant of the fetal umbilical vein.

Location and Structure

In most domestic mammals, the fissure for the round ligament is found:

• On the ventral aspect of the liver, specifically between the quadrate and left medial lobes in animals where these subdivisions are distinguishable (such as in dogs and pigs).

• The round ligament resides within this fissure and continues caudally within the free edge of the falciform ligament, which attaches the liver to the ventral abdominal wall and diaphragm.

Species Differences

• Dog and Cat: The fissure is well-defined. The round ligament is enclosed in the falciform ligament, which is prominent in younger animals and becomes progressively fatty and less distinct in adults.

• Ruminants (cattle, sheep, goats): The liver is more compact, and while the fissure is still present, it may be less pronounced due to the relatively smooth and non-lobated appearance of the ventral surface of the liver.

• Horse: The fissure is present but can be subtle. The round ligament follows a similar course within the falciform ligament.

• Pig: The liver is highly lobated, and the fissure is typically well-marked between lobes.

Developmental Context

Embryologically, the round ligament of the liver is the remnant of the left umbilical vein that carried oxygenated blood from the placenta to the fetus. After birth, this vein collapses and becomes a fibrous cord. Its path through the liver remains evident as the fissure for the round ligament.