The right hepatic artery (RHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver.

The proper hepatic artery bifurcates into the right and left hepatic arteries at or before reaching the porta hepatis. These are end arteries and supply the right and left halves of the liver respectively. The right hepatic artery passes upwards and turns to the right, crossing behind the common hepatic duct to enter Calot triangle ¹. It usually gives off the cystic artery within Calot triangle ^1,2 then turns upwards to enter the right lobe of the liver.

Within the liver, it divides into:

anterior segmental branch which supplies segments 5 and 8 and usually supplies a branch to segment 1 ¹
posterior segmental branch which supplies segments 6 and 7 ¹

Moynihan’s hump, also known as a caterpillar hump, is the descriptive term when the right hepatic artery forms a sinuous tortuosity occupying the majority of Calot triangle and may be at risk of damage during a cholecystectomy. It often lies in close proximity with the gallbladder neck.

NB: the hepatic segments were originally numbered by Roman numerals I to VIII, but the Arabic numerals 1 to 8 are now preferred ³

Variant anatomy

The right hepatic artery may be aberrant in one-third of cases, and is known to originate from the:

The right hepatic artery may also give rise to the middle hepatic artery, which usually arises from the left hepatic artery and supplies segments 4a and 4b.

An uncommon but important variant, the falciform artery, may arise from the right hepatic artery exiting the liver in the falciform ligament to supply part of the anterior abdominal wall.