Thoracic Lymph Nodes

Thoracic lymph nodes are a group of lymphatic structures located throughout the thoracic cavity, responsible for filtering lymph from the lungs, heart, esophagus, pleura, mediastinum, and thoracic wall. These nodes are part of the larger network of lymphatic drainage and play a critical role in immune surveillance, metastasis pathways, and infection containment within the thoracic region.

Main Groups of Thoracic Lymph Nodes

• Paratracheal lymph nodes
• Tracheobronchial lymph nodes (superior, inferior, left, and right)
• Bronchopulmonary (hilar) lymph nodes
• Pulmonary (intrapulmonary) lymph nodes
• Posterior mediastinal lymph nodes
• Prevascular and retrotracheal lymph nodes
• Parasternal lymph nodes
• Intercostal lymph nodes
• Diaphragmatic lymph nodes

1. Paratracheal Lymph Nodes

• Located on either side of the trachea
• Drain lymph from the trachea, esophagus, and mediastinal structures
• Continue superiorly with the deep cervical lymph nodes

2. Tracheobronchial Lymph Nodes

Subdivisions:

• Superior tracheobronchial: Above the carina
• Inferior tracheobronchial (carinal): Located at the bifurcation of the trachea
• Left and right tracheobronchial: At the hilum and main bronchi

These nodes receive lymph from the lungs, bronchi, and heart and are a major hub for lymphatic drainage from the lower respiratory tract.

3. Bronchopulmonary (Hilar) Lymph Nodes

• Located at the hilum of each lung
• Drain the pulmonary nodes and intrapulmonary structures
• Serve as an important checkpoint for lymph from each lung before it reaches the tracheobronchial group

4. Pulmonary (Intrapulmonary) Lymph Nodes

• Embedded along the segmental bronchi within the lung parenchyma
• Drain the peripheral lung tissue
• Flow into the bronchopulmonary (hilar) lymph nodes

5. Posterior Mediastinal Lymph Nodes

• Located along the thoracic aorta and esophagus in the posterior mediastinum
• Drain lymph from the posterior pericardium, esophagus, diaphragm, and posterior thoracic wall

6. Prevascular and Retrotracheal Lymph Nodes

• Prevascular nodes: Located anterior to the aortic arch and great vessels
• Retrotracheal nodes: Situated posterior to the trachea
• Drain structures of the anterior superior mediastinum

7. Parasternal Lymph Nodes

• Lie along the internal thoracic vessels near the sternum
• Drain the anterior thoracic wall, breasts (especially the medial quadrants), and upper abdominal wall

8. Intercostal Lymph Nodes

• Located near the heads of ribs along the intercostal spaces
• Drain the posterolateral thoracic wall
• Lymph may pass into the thoracic duct (posteriorly) or bronchomediastinal trunks

9. Diaphragmatic Lymph Nodes

• Found on the superior and inferior surfaces of the diaphragm
• Drain lymph from the lower lungs, pericardium, and upper abdominal structures

Lymphatic Drainage Pathways

Thoracic lymph nodes drain into larger lymphatic trunks and ducts:

• Right side: Drains into the right bronchomediastinal trunk → right lymphatic duct or subclavian vein
• Left side: Drains into the left bronchomediastinal trunk → thoracic duct → left subclavian vein

Clinical Significance

• Metastasis: Lung and breast cancers commonly spread through thoracic lymph nodes
• Lymphadenopathy: Enlargement seen in infections (e.g., tuberculosis), lymphoma, and sarcoidosis
• Staging of malignancies: Assessment of thoracic nodes is crucial in lung cancer TNM classification
• Imaging relevance: Visualized using CT, PET, and endobronchial ultrasound-guided biopsy (EBUS)

Topographic Summary

• Main groups: Paratracheal, tracheobronchial, hilar, pulmonary, posterior mediastinal, parasternal, intercostal, diaphragmatic
• Drainage: Lungs, pleura, esophagus, heart, thoracic wall, diaphragm
• Final drainage: Bronchomediastinal trunks → thoracic duct or right lymphatic duct