Porta of the liver

The porta of the liver (porta hepati; portal fissure) is the gateway through which vascular, biliary, and neural structures enter or exit the liver.

The porta hepatis is located on the visceral (posteroinferior) surface of the liver, typically within a transverse fissure. It serves as the passage for the following structures:

• The portal vein, which carries nutrient-rich blood from the gastrointestinal tract.

• The hepatic artery, supplying oxygenated blood to the liver.

• The hepatic ducts, draining bile from the liver.

• Autonomic nerves and lymphatics.

These structures are enveloped by a connective tissue sheath derived from the lesser omentum, forming part of the hepatoduodenal ligament.

Species-Specific Considerations

• Dog and Cat: The porta lies between the quadrate and caudate lobes. The portal vein enters centrally, flanked by the hepatic artery and bile duct. In dogs, the bile duct is generally ventral, the portal vein is dorsal, and the artery lies between them.

• Horse: The liver is relatively large and lies mostly to the right of the midline. The porta is located more dorsally, and the caudate lobe is prominent. The bile duct is singular, and there is no gallbladder.

• Ruminants (Cattle, Sheep, Goat): The porta is located on the right side due to the displacement of the liver. The portal vein is large, and the bile duct is well-developed. The bile duct drains directly into the duodenum. In cattle, the caudate process of the caudate lobe is particularly large and often overlies the porta.

• Pig: The porta is situated ventrally. The liver lobes are more distinctly separated, and the portal structures are well defined. Pigs also lack a gallbladder in some individuals, and the common bile duct may show variation.