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Lymphatic Trunks and Ducts

Trunci et ductus lymphatici

For medical students2 min readUpdated 2026-10-10

Lymphatic trunks and ducts are components of the cardiovascular system that complement the venous system. They ensure tissue drainage, lymph transport, and the removal of bacteria and foreign particles into the venous system.

FunctionSupplements venous return

Vessel WallConsists of three layers

Lymph DrainageEmpties into the venous angles

Thoracic DuctDrains lymph from most of the body

Structural Elements of the Lymphatic System

The lymphatic system consists of several sequential organizational levels of vessels, each performing a specific task:

Lymphatic capillaries (vasa lymphocapillaria). The smallest vessels with a wall consisting of a single layer of endothelium. Unlike blood capillaries, they are blind-ended. By anastomosing, they form capillary plexuses (retia lymphocapillaria) in all tissues and organs.
Lymphatic vessels (vasa lymphatica). Formed by the convergence of capillaries. Their walls are thinner than those of blood vessels and include three layers: the inner (tunica intima), the middle muscular (tunica media), and the outer adventitial (tunica externa). An important feature of these vessels is the presence of paired semilunar valves (valvulae lymphaticae) that ensure one-way lymph flow toward the heart.
Lymph nodes (nodi lymphoidei). Lymph from capillaries travels through vessels to the nodes, which act as biological filters.

Main Lymphatic Collectors

The bulk of the lymph collects into large collectors, which then drain into the venous system.

Thoracic duct (Ductus thoracicus). The largest lymphatic vessel. It drains lymph from the lower limbs, pelvis, abdomen, as well as the left upper limb, the left half of the thorax, head, and neck. It begins in the abdominal cavity with a dilation called the cisterna chyli, which receives the intestinal and lumbar trunks. The duct ascends through the thoracic cavity (thoracic part) into the neck (cervical part), where it empties into the left venous angle.
Right lymphatic duct (Ductus lymphaticus dexter). A short collector (about 1–1.5 cm long). It collects lymph from the upper right half of the body: the right upper limb, the right side of the thorax, head, and neck. The duct terminates by emptying into the right venous angle, which is formed by the confluence of the right internal jugular and right subclavian veins.

Lymphatic Trunks

Lymphatic trunks (trunci lymphatici) are large regional vessels that form the main ducts.

Tributaries of the Thoracic Duct:

Left and right lumbar trunks (truncus lumbalis sinister et dexter) — from the lower limbs and pelvis.
Intestinal trunks (trunci intestinales) — from the abdominal cavity organs.
Left jugular trunk (truncus jugularis sinister) — from the left half of the head and neck.
Left subclavian trunk (truncus subclavius sinister) — from the left upper limb.

Tributaries of the Right Lymphatic Duct:

Right jugular trunk (truncus jugularis dexter) — from the right half of the head and neck.
Right subclavian trunk (truncus subclavius dexter) — from the right upper limb.

Note: The bronchomediastinal trunk may also empty into the right lymphatic duct.

Main Regional Lymph Nodes

Lymph nodes are grouped according to their drainage region:

Head and neck: occipital, mastoid, superficial and deep parotid, submandibular, and submental nodes. In the neck, lymph collects into lateral superficial and deep cervical nodes, including prominent palpable nodes (e.g., jugulodigastric and jugulo-omohyoid nodes).
Upper limb and thorax: axillary nodes (the primary collector for the upper limb and breast), intercostal nodes, and paramammary nodes (the first stage of breast drainage).
Lower limb and pelvis: inguinal nodes (superficial and deep), draining the lower limbs and external genitalia, as well as external iliac nodes running along the corresponding vessels.

Frequently asked questions

Which lymphatic trunks empty into the thoracic duct?

The thoracic duct receives the lumbar trunks, intestinal trunks, as well as the left jugular and left subclavian trunks. The formation of the duct and further lymph collection involve the following major vessels:

Left lumbar trunk (truncus lumbalis sinister) — collects lymph from the left lower limb and pelvis.
Right lumbar trunk (truncus lumbalis dexter) — collects lymph from the right lower limb and pelvis.
Intestinal trunks (trunci intestinales) — drain lymph from the abdominal viscera.
Left jugular trunk (truncus jugularis sinister) — from the left half of the head and neck.
Left subclavian trunk (truncus subclavius sinister) — from the left upper limb.

At the level of which vertebrae does the thoracic duct begin (where is the cisterna chyli located)?

The thoracic duct begins at the level of the 11th thoracic to 2nd lumbar vertebra. Its initial dilation, the cisterna chyli, lies on the anterior surface of the vertebral bodies from L2 to T11 (predominantly at the level of the 1st and 2nd lumbar vertebrae). The cisterna is located near the right crus of the lumbar part of the diaphragm and is fused with it.

What are the anatomical topographic divisions of the thoracic duct?

Anatomically, the thoracic duct is divided into three topographic parts:

Abdominal part (pars abdominalis) — located retroperitoneally above the cisterna and passes through the aortic hiatus of the diaphragm.
Thoracic part (pars thoracica) — ascends through the thoracic cavity within the posterior mediastinum, running superiorly to the right of the aorta.
Cervical part (pars cervicalis) — the terminal segment in the neck region that forms the arch of the thoracic duct and empties into the left venous angle.

To which regional lymph nodes does lymphatic drainage of the breast occur?

Lymphatic drainage of the breast occurs into several groups of regional lymph nodes. The main drainage pathways include:

Axillary lymph nodes (nodi lymphatici axillares) — the primary pathway, receiving about 75–80% of the lymph (predominantly from the lateral quadrants).
Parasternal lymph nodes (nodi lymphatici parasternales) — receive lymph from the medial quadrants.
Supraclavicular lymph nodes — drain the superior regions of the gland.
Infraclavicular lymph nodes (nodi lymphatici infraclaviculares) — receive lymph from the posterior region.
Intercostal lymph nodes — from the posterior parts of the gland.
Paramammary lymph nodes (nodi lymphoidei paramammarii) and interpectoral lymph nodes (nodi lymphoidei interpectorales).

How do lymphatic capillaries differ from blood capillaries?

Lymphatic capillaries are blind-ended, whereas blood capillaries form part of a continuous, closed circuit between arteries and veins.

What structure marks the beginning of the thoracic duct?

The thoracic duct begins with a dilation in the abdominal cavity known as the cisterna chyli, which is formed by the confluence of the intestinal and lumbar trunks.

Where do the thoracic duct and right lymphatic duct empty?

The thoracic duct empties into the left venous angle, and the right lymphatic duct empties into the right venous angle. These angles are formed by the junction of the internal jugular and subclavian veins on their respective sides.

Go deeper

Topography of the cisterna chyli
Classification of cervical lymph nodes
Lymphatic drainage pathways of the breast
Connection of the lymphatic system with the superior vena cava
Structure of the valve apparatus in lymphatic vessels