Portal triad
Canalis portalis
Also known as: portal tract, portal canal, portal area
A portal triad is a connective-tissue tract at the corner of a liver lobule containing a branch of the hepatic portal vein, a branch of the hepatic artery and an interlobular bile duct. Lymphatics and nerves accompany them.
Overview
Each portal tract carries three main channels. A portal venule is the largest, with a thin wall and wide lumen. A hepatic arteriole is small, with a thick muscular wall. An interlobular bile duct is lined by cuboidal or low columnar cholangiocytes. Lymphatic vessels and autonomic nerves run alongside, so the tract is strictly a "pentad". A limiting plate of hepatocytes surrounds it. Blood leaves the tract to enter the sinusoids, and bile from the canaliculi enters it through the canals of Hering.
The term "portal triad" is also used at the macroscopic level for the three structures in the free edge of the hepatoduodenal ligament: the bile duct (anterior right), the hepatic artery proper (anterior left) and the hepatic portal vein (posterior).
- Location
Corners of the classic liver lobules; macroscopically, in the free edge of the lesser omentum.
Parts & subdivisions
- Terminal branch of the hepatic portal vein, bringing nutrient-rich blood.
- Hepatic arterioleTerminal branch of the hepatic artery, bringing oxygenated blood.
- Collects bile from the canaliculi via the canals of Hering.
Anatomy
- Histology
Connective tissue containing a large thin-walled vein, a small thick-walled artery and a cuboidal-epithelium duct, ringed by the limiting plate of hepatocytes.
Function
- Delivers portal and arterial blood to the lobule.
- Drains bile and lymph away from the lobule.
Clinical significance
Portal tract pathology
Interface (piecemeal) hepatitis, in which lymphocytes erode the limiting plate, marks chronic hepatitis. Primary biliary cholangitis (anti-mitochondrial antibodies, mostly middle-aged women) destroys the interlobular bile ducts. Portal-to-portal fibrous bridging signals advancing fibrosis.
Pringle manoeuvre
Compressing the macroscopic portal triad in the hepatoduodenal ligament (through the omental foramen) stops hepatic inflow and controls bleeding from the liver. If bleeding continues, the source is probably the hepatic veins or the IVC.
Test yourself
The portal triad in the free edge of the lesser omentum lies in which ligament?
- Hepatogastric ligament
- Hepatoduodenal ligament
- Falciform ligament
- Gastrosplenic ligament
Answer: Hepatoduodenal ligament
The hepatoduodenal ligament carries the bile duct (anterior right), the hepatic artery proper (anterior left) and the portal vein (posterior). It forms the anterior boundary of the omental foramen and is clamped in the Pringle manoeuvre.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.