What is the major lymphatic drainage route from the lungs to the venous system?

• A. Lymph drains from lungs directly into the systemic venous circulation.
• B. Lymph drains from lungs to the tracheobronchial nodes and then to the thoracic duct or right lymphatic duct.
• C. Lymph drains from lungs to the axillary nodes.
• D. Lymph drains from lungs to tracheobronchial nodes, then to the thoracic duct (left) or right lymphatic duct (right).

Answer: (D)

Lymph from lung tissue follows a chain of nodes before reaching the bloodstream. It drains from the intrapulmonary and bronchopulmonary lymphatics into the regional tracheobronchial (mediastinal) nodes. From there, most lymph from the left side and much from the lower body collects into the thoracic duct, which empties into the left venous angle (left subclavian–internal jugular junction). Lymph from the right side of the thorax and head/neck can drain via the right lymphatic duct, which enters the right venous angle. So, the major route is from the lungs to tracheobronchial nodes, then to the thoracic duct (left) or the right lymphatic duct (right) before returning to the venous system.