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Topographic Anatomy · Topographic Anatomy of the Abdomen

Topographic anatomy of the extrahepatic biliary ducts

Ductus choledochus, ductus cysticus, ductus hepaticus communis

Extrahepatic bile ducts ensure the transit of bile from the porta hepatis to the duodenum. The key collector is the common bile duct (ductus choledochus), which features a complex topography and closely contacts major vessels and the pancreas along its course.

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Parts of the ductAnatomically, the common bile duct is divided into 4 consecutive parts.
Length of the choledochusThe length of the common bile duct typically ranges from 5 to 8 centimeters.
Duct compressionHead of the pancreas cancer causes obstructive jaundice due to compression of the common bile duct.
Site of entryThe duct opens at the summit of the major duodenal papilla in the duodenum.
4 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Formation of the biliary tract

The initial stage of extrahepatic bile duct formation occurs in the region of the porta hepatis. Here, the right and left hepatic ducts merge to form the common hepatic duct (ductus hepaticus communis).

A short distance further down, about 2.5–3.0 cm from the junction of the lobar branches, the cystic duct (ductus cysticus) empties into the hepatic duct. It is at this point that the common bile duct (ductus choledochus) begins.

The anatomy of the cystic duct varies significantly. With an average length of about 3.9 cm and a diameter of 4 mm, its entry into the common hepatic duct can occur in several ways:

  • At an acute or obtuse angle.
  • Parallel to the common hepatic duct (running together for a certain distance before final fusion).
  • In a spiral course, where the cystic duct loops around the hepatic duct.

Supraduodenal and retroduodenal parts

The common bile duct itself (5–8 cm long) is traditionally divided into four topographical parts, each with unique syntopy.

  1. Supraduodenal part. Begins directly from the junction of the hepatic and cystic ducts and extends to the upper margin of the duodenum. This segment runs in the right margin of the hepatoduodenal ligament (lig. hepatoduodenale). The length of this part ranges from 0.3 to 3.2 cm.
  2. Retroduodenal part. Is about 1.8 cm long and lies behind the superior part of the duodenum, 3–4 cm away from the pylorus of the stomach. Its topographical layout is as follows: the portal vein passes superior and to the left of the duct, while the gastroduodenal artery (a. gastroduodenalis) runs inferior and to the right.
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Pancreatic and intramural parts

Below the retroduodenal part, the duct interacts with the pancreas and the intestinal wall.

  1. Pancreatic part (about 2.9 cm long). Passes either directly within the parenchyma of the pancreatic head or lies on its posterior surface in the so-called retropancreatic (interstitial) groove. In this zone, the duct lies adjacent to the right margin of the inferior vena cava, while the portal vein crosses it obliquely from the left side.

Clinical significance: close adherence to the pancreatic tissue results in the duct being rapidly compressed by a tumor of the pancreatic head. This blocks bile outflow and causes mechanical (obstructive) jaundice.

  1. Interstitial (intramural) part. This is the terminal part, approximately 1.6 cm long. The duct obliquely pierces the posterior wall of the descending part of the duodenum at the level of its middle third. It terminates at the summit of the major duodenal papilla (papilla duodeni major). As a rule, before entering the intestinal lumen, the choledochus merges with the main pancreatic duct. This forms the hepatopancreatic ampulla (ampulla hepatopancreatica), surrounded by its own muscular sphincter — the sphincter of the ampulla (m. sphincter ampullae hepatopancreaticae).

Briefly: answers to topical questions

What is the syntopy of the elements within the hepatoduodenal ligament at the level of the supraduodenal part of the choledochus?

At the level of the supraduodenal part, the common bile duct lies in the right margin of the hepatoduodenal ligament (lig. hepatoduodenale). This part of the duct starts from the junction of the hepatic and cystic ducts and extends to the duodenum, with a length ranging from 0.3 to 3.2 cm. Topographical relationships (syntopy) with other blood vessels and elements within the ligament itself at this level are not specified in the sources.

Which blood vessels does the retroduodenal part of the choledochus contact?

The retroduodenal part of the common bile duct, located behind the superior part of the duodenum for about 1.8 cm, contacts two major blood vessels.

  • Portal vein — located superior and to the left of the bile duct.
  • Gastroduodenal artery (a. gastroduodenalis) — located inferior and to the right of it.

Which sphincter muscles regulate the flow of bile in the terminal part of the choledochus?

The sources indicate that a sphincter is located around the hepatopancreatic ampulla — m. sphincter ampullae hepatopancreaticae.

Where does lymph drainage from the extrahepatic bile ducts lead?

Lymph from the liver, gallbladder, and bile ducts drains into the hepatic and cystic lymph nodes (nodi lymphoidei hepatici), and subsequently into the celiac, gastric, pyloric, and pancreatoduodenal nodes.

How to memorize

For quick memorization of the 4 parts of the common bile duct, use the rule: Supraduodenal (above the duodenum), Retroduodenal (behind the duodenum), Pancreatic (in the pancreas), Interstitial (within the wall).

Class and exam questions

Which elements merge to form the ductus choledochus?

The common bile duct is formed by the union of the common hepatic duct (ductus hepaticus communis) and the cystic duct (ductus cysticus).

Where exactly is the supraduodenal part of the choledochus located?

This part runs in the right free margin of the hepatoduodenal ligament (lig. hepatoduodenale), extending from the point of duct formation to the duodenum.

What is the clinical significance of the pancreatic part of the duct?

Since this part runs within the thickness or along the posterior surface of the pancreatic head, the development of a tumor (cancer) in this area easily compresses the duct, leading to obstructive jaundice.

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What else to study on this topic

  • Anatomical variations of cystic duct insertion (parallel, spiral).
  • Syntopy of elements in the retroduodenal space (portal vein and a. gastroduodenalis).
  • Relationship of the pancreatic part of the choledochus to the inferior vena and portal veins.
  • Topography and structure of the hepatopancreatic ampulla and its sphincter.

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Other topics in the section "Topographic Anatomy of the Abdomen"

Topographic Anatomy of the AbdomenProjection of organs onto the abdominal wallTopographic anatomy of the anterolateral abdominal wallExternal oblique abdominal muscleInternal oblique abdominal muscleRectus abdominis muscleEndoabdominal fascia and extraperitoneal adipose tissueRelief of the posterior surface of the anterior abdominal wallBlood supply to the anterolateral abdominal wallLymphatic system and innervation of the anterior abdominal wallLinea albaTopographic anatomy of the umbilical regionTopography of the abdominal cavity organsInguinal canalInguinal trianglePeritoneal cavitySupramesocolic compartmentTopographic anatomy of the liverBlood supply and innervation of the liverTopographic anatomy of the portal veinTopographic anatomy of the gallbladderAbdominal part of the esophagusTopographic anatomy of the stomachLigamentous apparatus of the stomach
The entire section "Topographic Anatomy of the Abdomen"

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