Bronchomediastinal Lymph Trunks

The bronchomediastinal lymph trunks are paired lymphatic channels that collect lymph from deep structures of the thorax, including the lungs, heart, trachea, and mediastinum. They represent the final common drainage path for many thoracic lymph nodes before the lymph enters the venous system. Each side of the thorax contains one bronchomediastinal trunk—right and left—which differ slightly in their termination points.

Origin

The bronchomediastinal trunks arise from the convergence of several thoracic lymph node groups, including:

• Paratracheal lymph nodes
• Tracheobronchial lymph nodes
• Hilar (bronchopulmonary) lymph nodes
• Posterior mediastinal lymph nodes

Course

Each trunk ascends superiorly through the superior mediastinum alongside the trachea and great vessels. They are relatively short ducts that travel in close proximity to the internal jugular and subclavian veins and terminate at variable sites based on the side of the body.

Termination

Right Bronchomediastinal Trunk

• Usually empties into the right lymphatic duct
• Alternatively, it may drain directly into the junction of the right internal jugular and right subclavian veins

Left Bronchomediastinal Trunk

• Usually joins the thoracic duct
• May also drain directly into the left venous angle (junction of the left internal jugular and left subclavian veins)

Function

The bronchomediastinal trunks are responsible for transporting lymph from the thoracic viscera and part of the anterior chest wall into the systemic venous circulation. They play a crucial role in immune surveillance and fluid balance in the thoracic cavity.

Drainage Territories

• Lungs and bronchi
• Heart and pericardium
• Esophagus (thoracic portion)
• Trachea and mediastinum
• Diaphragm (superior surface)

Relations

• Medial: Trachea and esophagus
• Lateral: Lungs and pleura
• Anterior: Great vessels (aortic arch, brachiocephalic vein, subclavian vessels)
• Posterior: Vertebral column and thoracic duct (on the left)

Clinical Significance

• Lymphadenopathy: Obstruction of these trunks by enlarged lymph nodes can lead to thoracic duct or right lymphatic duct flow issues
• Metastasis routes: Common pathways for spread of lung, esophageal, and breast cancers
• Thoracic surgeries: Injury to these trunks can impair lymphatic drainage, leading to chylothorax or lymphatic leakage

Topographic Summary

• Number: Paired (right and left)
• Origin: Confluence of tracheobronchial, paratracheal, and hilar lymph nodes
• Termination: Right into right lymphatic duct or venous angle; left into thoracic duct or venous angle
• Function: Drain thoracic viscera into systemic venous circulation