Most common arrangement

In the classic arrangement, occurring with a frequency of approximately 70%, a singular cystic artery originates from the geniculate flexure of the right hepatic artery in the upper portion of the hepatobiliary triangle

Hepatobiliary triangle

The hepatobiliary triangle is an anatomic space bordered by the common hepatic duct medially, the cystic duct inferiorly and the superior border to the cystic artery .-Eponym:...

. A site of origin from a more proximal or distal portion of the right hepatic artery is also considered relatively normal.

After separating from the right hepatic artery, the cystic artery travels superiorly to the cystic duct

Cystic duct

The cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length...

 and produces 2 to 4 minor branches, known as Calot’s arteries, that supply part of the cystic duct and cervix of the gallbladder before dividing into the major superficial and deep branches at the superior aspect of the gallbladder neck:

• The superficial branch (or anterior branch) passes sub-seriously over the left aspect of the gallbladder.
• The deep branch (or posterior branch) runs between the gallbladder and gallbladder fossa, terminating at the peritoneum attached to the liver surface.

Double cystic artery

When superficial and deep branches of the cystic artery do not share a common origin it is defined as a double cystic artery occurring with a frequency of 15%.

The deep branch consistently arises from the right hepatic artery which is generally also the source of origin of the superficial branch, however in some cases it has been found to initiate from the anterior segmental artery, middle hepatic artery, left hepatic artery, superior mesenteric artery

Superior mesenteric artery

In human anatomy, the superior mesenteric artery arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies the intestine from the lower part of the duodenum through two-thirds of the transverse colon, as well as the pancreas.-Location...

, gastroduodenal artery

Gastroduodenal artery

In anatomy, the gastroduodenal artery is a small blood vessel in the abdomen.It supplies blood directly to the pylorus and proximal part of the duodenum, and indirectly to the pancreatic head .It most commonly arises from the common hepatic artery of the celiac trunk, but there are...

 or retroduodenal artery.

Approximately half of superficial cystic arteries have been shown to enter through the hepatobiliary triangle, while deep cystic arteries are often quite small in length and diameter. Tripling of the cystic artery is very rare, occurring in between 0-0.3% of cases.

Aberrant origin of the right hepatic artery

Unusual anatomy of the right hepatic can itself affect the path and form of the cystic artery, with the most frequent variation resulting from an aberrant origin of the right hepatic artery which is described in between 2-16% of cases.

Generally this anomalous source is the superior mesenteric artery or more rarely the abdominal aorta, producing what has been described as a "replacing right hepatic artery", passing through the hepatobiliary triangle and running posterior and parallel to the cystic duct.

Because of the close proximity to the gallbladder to the (replacing) right hepatic artery a "caterpillar" or "Moynihan's" hump may form and this artery generally produces multiple short cystic branches rather than a single cystic artery.

Left hepatic artery

The cystic artery can arise from the left hepatic artery, and in such a case it usually travels through a passage of liver parenchyma

Parenchyma

Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, f. Greek παρέγχυμα - parenkhuma, "visceral flesh", f. παρεγχεῖν - parenkhein, "to pour in" f. para-, "beside" + en-, "in" + khein, "to pour"...

, approaching the neck of the gallbladder, before bifurcating into ascending (or superior) and descending (or inferior) branches. This situation is found in roughly 1% of cases.

This form of the cystic artery does not pass through the hepatobiliary triangle and has been found located both anteriorly and posteriorly to the common hepatic duct.

Recurrent cystic artery

In less than 1% of patients a form known as a recurrent cystic artery is found – the cystic artery arises from the left hepatic artery and passes through either the cholecystoduodenal or cholecystocolic ligaments (connecting the gallbladder to the duodenum and transverse colon respectively), follows the right edge of the hepatoduodenal ligament

Hepatoduodenal ligament

The hepatoduodenal ligament is the portion of the lesser omentum extending between the porta hepatis of the liver and the superior part of the duodenum.Running inside it are the following:* hepatic artery proper* hepatic portal vein* common bile duct...

, and connects to the fundus of the gallbladder before descending to supply the body and neck.

Low-lying cystic artery

When a single cystic artery arises from gastroduodenal artery it forms a configuration is known as low-lying cystic artery, as it passes inferior to the cystic duct through the cholecystoduodenal ligament, and therefore remains outside the hepatobiliary triangle.

This condition has alternatively been described as an inferior cystic artery and transposition of the cystic artery and duct with a prevalence at approximately 5%.

In 25% of these patients with this course there will be a secondary arterial supply to the gallbladder, with the low-lying artery acting as the equivalent of the posterior branch.

Clinical significance

It must be identified and ligated in operations that remove the gallbladder (cholecystectomies).

External links

• Cystic artery - thefreedictionary.com