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Thoracic and mediastinal lymph nodes and lymphatics

Recommended video: Lymphatics of the female breast [09:51]
Lymph vessels and nodes of the female breast.

Lymph nodes and associated vessels are widely distributed throughout the body. They are strategically located at areas at which the body would be susceptible to pathogenic invasion. Furthermore, they screen interstitial fluid that is being returned to the general circulation for potentially harmful agents.

The main focus of this article will be on the lymphatic system associated with the thoracic cavity and mediastinum.

  1. Overview
  2. Anterior thoracic wall
    1. Lymphatic drainage of the skin
    2. Lymphatic drainage of the breast
    3. Parasternal lymph nodes
    4. Diaphragmatic lymph nodes
  3. Posterolateral thoracic wall
    1. Intercostal lymph nodes
    2. Thoracic duct
    3. Right lymphatic duct
  4. Intrathoracic lymph nodes (lower respiratory tract lymphatics)
  5. Heart
  6. Oesophagus
  7. Thymus
  8. Clinical application
    1. Cancer
    2. Anatomic variation of the thoracic duct
    3. Chyle fistula
  9. Sources
+ Show all


The thorax is the region of the body extending from the base of the neck and thoracic inlet (the latter being at the supraclavicular fossae) to the diaphragm (marked anteriorly by the xiphisternal joint).

Within the thoracic cavity is the mediastinum. The mediastinum is the region of the thorax between the lungs. It extends from the level of the first rib, superiorly, to the diaphragm, inferiorly. Additionally, it is bounded anteriorly by the posterior surface of the manubrium of sternum, and posteriorly by the anterior surface of the thoracic vertebra.

The mediastinum is further subdivided into four compartments. Firstly, horizontal line traveling anteroposteriorly at the level of the manubriosternal angle of Luis divides it into the superior and inferior mediastina.

Superior mediastinum (ventral view)

The inferior mediastinum is further subdivided in three subcompartments:

  •  the anterior mediastinum, found anterior to the heart and posterior to the sternum;
  • the posterior mediastinum, located anterior to the thoracic vertebrae (lower border of T4 to T12) and posterior to the heart.
  • the middle mediastinum is occupied by the heart, its pericardium along with segments of the great vessels of the heart, the tracheal bifurcation and the main bronchi.

Special attention will be paid to drainage pathways of the skin and other superficial structures, as well as the viscera of the thorax and mediastinum.

Challenge yourself and identify the main organs of the lymphatic system with this quiz.

Anterior thoracic wall

The anterior thoracic wall extends craniocaudally from the level of the clavicle and jugular notch to the level of the xiphisternal joint. It also extends bilaterally from one anterior axillary line to the other.

Bony thorax in a cadaver: Overview of the components of the thoracic wall. You can also see the superior thoracic aperture, which is the passage between the neck and the thoracic cavity.

Lymphatic drainage of the skin

The skin of the thorax achieves lymphatic drainage via a superficial and a deep system.

  • The superficial lymphatic vessels converge in the subcutaneous space and take lymph back to the axillary lymph nodes.
  • The deep lymphatic system, on the other hand, drain to the intercostal nodes, as well as to the parasternal and diaphragmatic nodes.

Lymphatic drainage of the breast

Another clinically relevant lymphatic pathway associated with the anterior chest wall is that of the breast lymphatics. The breasts, or mammary glands, are anatomically and functionally dichotomous structures associated with reproduction and human sexuality.

Of note, breast lymph channels are avalvular; therefore any occlusion (secondary to tumors) can result in reversal of blood flow. There are numerous periductal and perilobular vessels that parallel the venous tributaries of the breast.

In both males and females, the breast can be divided into quadrants.

  • The regions superior to the nipple-areolar complex are the upper quadrants, while those inferior to the complex are the lower quadrants.
  • Similarly, the quadrants lateral to the complex are outer quadrants and those medial to it are the inner quadrants.
Interpectoral axillary lymph nodes (ventral view)

From this notion, the inner quadrants, and the lower outer quadrant drain primarily to the parasternal and inframammary lymph nodes. The upper outer and part of the lower outer quadrants drain primarily to the axillary nodes. The medial part of each breast also drains to the internal thoracic lymph nodes, which subsequently drains to the superior and inferior epigastric lymph pathways to the groin. Furthermore, the left and right breasts, although symmetrical, have different terminal lymph drainage points. The left breast lymphatics drain via the thoracic duct to the left subclavian vein, while the right breast drains to the right jugulo-subclavian junction. Additionally, lymphatic channels originating from one mammary gland may cross the midline and terminate in nodes associated with the contralateral breast.

Parasternal lymph nodes

Parasternal lymph nodes (ventral view)

The parasternal lymph nodes are a group of four to five nodes residing at the anterior limit of the intercostal space, adjacent to the thoracic arteries.

In addition to draining the breast, they also receive lymph from deep structures of the epigastrium, deeper parts of anterior thoracic wall and the cranial surface of the liver. The efferent vessels of these nodes then anastomose with vessels associated with the tracheobronchial and brachiocephalic nodes to form the bronchomediastinal trunk. This vessel has a variety of terminal points, including in the jugular or subclavian veins, or at the junction of these vessels (jugulo-subclavian junction), the left thoracic duct or the right lymphatic duct.

Diaphragmatic lymph nodes

Additionally, there are lymph nodes located on the thoracic (superior) surface of the diaphragm known as diaphragmatic nodes (also known as superior phrenic nodes). These nodes are further subdivided into anterior, lateral and posterior groups.

  • The anterior diaphragmatic group of nodes are comprised of about three nodes posterior to the xiphoid process. There are additional small nodes at the level of the seventh costochondral junction. Afferent lymphatic vessels to these nodes arise from the anterior lymph vessels of the diaphragm; while efferent lymphatic vessels from the same pass to the parasternal nodes.
  • The lateral group of thoracic diaphragmatic lymph nodes are further subdivided into left and right groups of two or three nodes. They are adjacent to the point at which the phrenic nerves pierce the diaphragm. The right group of nodes, which are juxtaposed to the pericardium and the distal part of the intrathoracic inferior vena cava, drain the central diaphragm and the convex surface of the liver. They subsequently drain to the parasternal, posterior mediastinal and brachiocephalic lymph nodes.
  • The posterior group of diaphragmatic nodes will be discussed below with the nodes of the posterolateral thoracic wall.

Posterolateral thoracic wall

The posterolateral thoracic wall extends superoinferiorly from the level of the T1 vertebra to the T12 vertebra, and bilaterally from one anterior axillary line to the next across the posterior surface of the thorax.

Intercostal lymph nodes

The intercostal lymph nodes have the responsibility of draining the posterolateral chest. They can be found at the costovertebral junction along the thoracic vertebrae. The efferent vessels of the nodes of the caudal four to seven intercostal spaces anastomose to form a single trunk that travels inferiorly and inserts into the proximal part of the thoracic duct. Efferent lymphatics of node of the cranial left and right intercostal spaces drain to the thoracic duct and right lymph trunks, respectively.

Posterior thoracic diaphragmatic group of nodes are found on the posterior surface of the diaphragmatic crura. They form a communication between the posterior mediastinal and lateral aortic nodes.

Thoracic duct

The thoracic duct and right lymphatic duct are two major lymph channels found close to the posterior thoracic wall.

The thoracic duct commences at the L1/L2 level, anterior and slightly to the right of the vertebral bodies and travels about 38 to 45 cm to the base of the neck in adults. The vessel is wider at its origin, where the lumbar lymph trunks unite. Occasionally, there is a lymphatic cistern (a swelling or waterproof receptacle) known as the cisterna chyli.

Thoracic duct (ventral view)

The thoracic duct becomes narrower as it moves cranially before dilating again prior to terminating in the jugulo-subclavian junction. The thoracic duct contains several valves at high pressure points where some tributaries join the vessel to prevent the reflux of lymph. The thoracic duct travels adjacent to the azygous and hemiazygous veins, and the aorta in the retrocrural part of the diaphragm.

It continues to the right of the midline of the thoracic cavity through the posterior mediastinum, with the thoracic aorta to its left and the azygous vein on the right. Posteriorly related structures include the vertebral column, terminal hemiazygous and accessory hemiazygous veins, and the right intercostal arteries; while anteriorly related structures include the diaphragm and oesophagus.

Accessory hemiazygos vein (ventral view)

The fifth thoracic vertebra marks the point at which the thoracic duct courses towards the left as it enters the superior mediastinum, before progressing towards the thoracic inlet. It is noteworthy that at this point the thoracic aorta is located to the right of the duct.

At the seventh cervical vertebra, it curves laterally, after which it courses posterior to the left common carotid artery, internal jugular vein and vagus nerve (CN X) before descending towards and terminating in the jugulo-subclavian junction. It is not uncommon for the duct to terminate in either the subclavian or internal jugular veins, rather than the junction of the two. As previously mentioned, there are several tributaries to the thoracic duct. These include:

  • Bilateral vessels from the intercostal lymph nodes of the caudal 6 – 7 intercostal spaces descending to join the duct. 
  • Bilateral lumbar lymph vessels travelling cranially from the superior aortic nodes to anastomose and form the thoracic duct. 
  • Efferents from the cranial 5 – 6 intercostal nodes on the left hand side. 
  • Mediastinal nodes from a myriad of nodal groups. 
  • The left jugular trunk and left bronchomediastinal trunk on occasion drain into the thoracic duct, but may also drain into their respective independent venous openings.

Right lymphatic duct

The right lymphatic duct has several anatomical presentations including unilateral or bilateral termination, duplicate ducts or left-sided termination. It is approximately 1.25 cm long and travels on the medial edge of scalenus anterior. The vessel then terminates in the right jugulo-subclavian junction. Like the thoracic duct, the right lymphatic duct also has semilunar valves at its opening to prevent the reflux of lymphatic fluid. Afferents to this vessel arise from the right jugular and subclavian trunks as well as from the right upper limb (lateral group of axillary nodes). The right side of the heart, right lung, and the right sides of the head, neck and thorax also drain into the right lymphatic trunk.

Intrathoracic lymph nodes (lower respiratory tract lymphatics)

The intrathoracic part of the respiratory system is comprised of the distal half of the trachea (commencing at the inferior border of T1) and its subsequent branches as well as the lungs and their associated pleura. These structures are fundamental to the processes of gaseous exchange and respiration.

There are several groups of nodes associated with lymphatic drainage of the lungs and conducting airway. These are collectively known as the tracheobronchial lymph nodes. They include:

  • the pretracheal and paratracheal nodes are located anterior to, and along the sides of the trachea (respectively);
  • the superior tracheobronchial nodes, are seen at the superior border of the bifurcation of the trachea;
  • the bronchopulmonary or hilar nodes, are located in the hilum of the lungs where the main-stem bronchi enter the lungs,
  • the pulmonary or intrapulmonary nodes, are just deep to the hilum and surround the bronchi;
  • and the inferior tracheobronchial or subcarinal nodes are inferior to the carina of the trachea.

The trachea drains its lymph to the pretracheal and paratracheal lymph nodes. Drainage of the lungs can be considered from superficial to deep. The most superficial layer, which is the parietal pleura, drains its lymphatic content ventrally to the parasternal nodes and dorsally to the intercostal nodes. The visceral pleural, on the other hand, drain via the deep pulmonary plexus to the hilar nodes.

There are superficial and deep sub-pleural plexuses that have few communications with each other (one being at the hilar region). There are additional small channels that are capable of dilating to facilitate divergence of deep lymph to the superficial system in the instance that there is an obstruction in the former system. The efferent vessels of the superficial plexus follow the borders of the lungs and margins of the fissures until they terminate in the bronchopulmonary nodes. The upper lobes typically drain to the superior tracheobronchial nodes, while the inferior lobes drain to the subcarinal nodes, located inferior to the carina, or bifurcation of the trachea.


The heart is the muscular, four-chambered, autonomic pump responsible for circulating blood throughout the body. Like any other organ, it also has lymphatic fluid that needs to be drained from its interstitial space.

The lymphatics of the heart are divided into three plexuses found in the subepicardial, myocardial and subendocardial spaces.

The subepicardial plexus is the recipient of efferent lymphatics arising from the subendocardial and myocardial plexuses. After receiving those tributaries, the subepicardial plexuses give rise to the left and right cardiac collecting trunks. The trunks arising on the left side travel superiorly in the anterior interventricular groove while receiving afferents from the right and left ventricles. In the atrioventricular groove, the trunks merge with the tributaries from the diaphragmatic surface of the left ventricle. This newly formed vessel then courses between the pulmonary artery and left atrium before terminating in the tracheobronchial nodes.

Brachiocephalic lymph node (ventral view)

The right trunks receive tributaries from the right border of the heart, diaphragmatic surface of the right ventricle and the right atrium. The newly formed vessel then travels adjacent to the right coronary artery in the atrioventricular groove. It subsequently courses anterior to the ascending aorta on its way to the brachiocephalic node on the left.


The oesophagus is a musculo-tubular structure that commences that the caudal end of the inferior pharyngeal constrictors and terminates at the cardio-oesophageal junction. The point of origin is located at the lower border of the cricoid cartilage, while the terminal point is at the T11 vertebra (intraabdominal). The 25 cm tube spans the cervical and thoracic regions to allow communication between the pharynx and the stomach, which facilitates eating and digestion.

Lymph nodes of the oesophagus – also known as the juxtaoesophageal nodes – are continuous craniocaudally and are found bilateral to the structure. There are submucosal lymphatic channels that facilitate drainage of the oesophagus. Since the oesophagus can be divided into cervical, thoracic and abdominal parts, their lymphatic channels also drain to different anatomical regions.

  • the cervical part drains to the paratracheal and deep cervical nodes
  • the thoracic part drains to the posterior mediastinal nodes and,
  • The abdominal part drains to the left gastric nodes.
Abdominal part of esophagus (ventral view)


The thymus is a derivative of the third pharyngeal pouches. This encapsulated, bilobular structure – along with bone marrow – are the only two primary lymphoid organs in the body. The majority of the thymus is found in the superior mediastinum, with some extension into the anterior part of the inferior mediastinum. The thymus may also extend superiorly toward the thyroid gland and may also communicate with the same via the thyrothymic ligament. The thymus is largest earlier in life and undergoes progressive fibrofatty degeneration with time. It is primarily concerned with the production of T-lymphocytes (thymus-processed).

Thymus (ventral view)

There are no afferent lymphatic vessels leading to the thymus. However, it gives off efferent lymphatic channels that originate from its corticomedullary junction, as well as directly from the medulla. The channels travel in the extravascular spaces with the arteriovenous supply of the gland. Thymic efferent lymphatics subsequently terminate in parasternal, brachiocephalic and tracheobronchial nodes.

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