Connection lost. Please refresh the page.
Get help How to study Login Register
Ready to learn?
Pick your favorite study tool

Thoracic duct

Recommended video: Introduction to the lymphatic system [14:10]
Overview of the anatomy, function and main structures of the lymphatic system.

The thoracic duct is the largest lymphatic vessel in the human body. Around 75% of the lymph from the entire body (aside from the right upper limb, right breast, right lung and right side of the head and neck) passes through the thoracic duct.

The cells of the immune system circulate through the lymphatic system. Also, large molecular products of digestion, like fats, first need to be absorbed into the lymphatic system, and then to reach the systemic circulation through the venous system. The lymphatic system is essential for the drainage of tissue fluid, and the passage of lymph around the body.

Key facts about the thoracic duct
Anatomy Location: paravertebral from T12 to the root of the neck
Tributaries Main tributaries: left and right lumbar lymph trunks, left and right intestinal lymph trunks (their confluence is called cysterna chyli)
Additional tributaries: mediastinal lymph trunks, left jugular trunk, left bronchomediastinal trunk, left subclavian trunk
Drainage Drains from: 75% of the body -> all region except for the right arm, right breast, right lung, right side of the head and neck (which are drained by the right lymphatic duct)
Drains to: venous angle (Pirgoff's angle) between left subclavian vein and left internal jugular vein
Clinical relations Chylothorax, Virchow's node, thoracic duct fistula

This article will look at the anatomy of the thoracic duct, including the function, location and drainage. We will also discuss function and clinical relevance.

  1. Embryology
  2. Anatomy
    1. Characteristics, course and location
    2. Tributaries
    3. Variations
  3. Clinical points
    1. Chylothorax
    2. Virchow’s node
    3. Thoracic duct fistula
  4. Sources
+ Show all


The thoracic duct develops during the seventh and eighth week of gestational life from two vessels anterior to the aorta, which become the left and right embryonic thoracic ducts. The left one gives rise to the upper third of the adult thoracic duct while the lower two-thirds of the adult duct arise from the right embryonic thoracic duct.

The duct connects with lymph nodes over time. The thoracic duct wall and lymph nodes are not fully formed at birth. Disturbances in formation result in various structural variations. The first lymph sacs that develop are the paired jugular lymph sacs located at the border between the internal jugular and subclavian veins. A single retroperitoneal lymph sac also develops at the root of the mesentery, with the cisterna chyli also developing behind the retroperitoneal sac. The lymph vessels grow out from the lymph sacs, along the major veins of the head, neck, and arms. Longitudinal lymph vessels that ultimately form the thoracic duct gradually connect the cisterna chyli and the jugular lymph sacs.


Characteristics, course and location

The thoracic duct (also known as van Hoorne’s canal) is the largest lymphatic vessel of the lymphatic system of the body. It is approximately 40 cm in length in adults, and approximately 5 mm in width at its abdominal origin.

The thoracic duct extends from the twelfth thoracic vertebra to the root of the neck. The thoracic duct is formed from the abdominal confluence of the left and right lumbar lymph trunks, as well as the left and right intestinal lymph trunks between T12 and L2. If the confluence of lymph trunks is saccular, it is referred to as cisterna chyli. The action of breathing helps chyle flow up the thoracic duct. The duct also contains smooth muscle within its walls, as well as interval valves (much like large veins), which prevent backflow of lymph.

Need to refresh your knowledge of the basic anatomy of the digestive system? Our digestive system quizzes and free learning tools have your back. 

The thoracic duct crosses the diaphragm at the aortic hiatus at the level of the twelfth thoracic vertebra. The aortic opening is located in the posterior mediastinum, and is formed either side by the left and right crura of the diaphragm. The duct continues to ascend, between the thoracic aorta on the left, and the azygous vein on the right, and crosses over to the left side between the fourth and sixth thoracic vertebrae. From this point, the duct ascends behind the aortic arch and the left subclavian artery. The duct will also lie anterior to the anterior scalene muscle and left phrenic nerve before its final destination. The fluid drains at the level of the venous angle (Pirogoff’s angle) between the left subclavian vein and the left internal jugular vein, where it reenters the systemic venous circulation. It is often dilated or enlarged at its terminal segment. There is a bicuspid valve located at the junction of the thoracic duct with the draining vein (e.g. left internal jugular vein or left subclavian vein depending on anatomical variations), which prevents backflow of venous blood into the lymphatic system.

Within the thoracic duct, you find a milky white fluid containing both emulsified fats, and the lymph fluid found in the rest of the lymphatic system. This fluid is called chyle. The thoracic duct drains the lymph from 75% of the body, aside from the right upper right limb, right breast, right lung and right side of the head and neck (which are drained by the right lymphatic duct).

Neurovasculature of the neck and superior thorax: Notice the location of the thoracic duct. During a cadaveric dissection, the thoracic duct resembles a small vein without blood in it. It is also thin and easily torn.


The thoracic duct drains lymph from the right and left descending thoracic lymph trunks, originating from the lower 6 intercostal spaces (6 to 11). The duct also receives lymph from intercostal spaces 1 to 5 via the upper intercostal lymph trunks. Additional tributaries include the: 

  • mediastinal lymph trunks
  • left jugular trunk,
  • left bronchomediastinal trunk
  • left subclavian trunk

Learn the lymphatic system with the following video lecture and quiz. 


The thoracic duct occasionally divides into a right and left duct, with the left entering the venous system as normal, and the right draining into the right subclavian vein. The duct may also drain into the left internal jugular vein, or into the left brachiocephalic vein.

Check what you know about the thoracic duct and other elements of the lymphatic system with our quiz.

Thoracic duct: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more.

Kim Bengochea Kim Bengochea, Regis University, Denver
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

Register now and grab your free ultimate anatomy study guide!