Lymphology Association of North America (LANA) Practice Exam

Which lymph trunks enter the thoracic duct just before it enters the subclavian vein?

1. Left subclavian, left jugular, and left bronchomediastinal trunks

2. Left subclavian and left and right jugular trunks

3. Bilateral subclavian trunks

4. Bilateral jugular trunks

The correct answer is: Left subclavian, left jugular, and left bronchomediastinal trunks

The correct answer identifies the specific lymphatic trunks that converge into the thoracic duct just before it drains into the subclavian vein. The thoracic duct is the main vessel responsible for transporting lymph from the left side of the body and areas of the right side above the diaphragm. The left subclavian trunk, left jugular trunk, and left bronchomediastinal trunk are crucial as they collect lymph from significant regions: the left subclavian trunk gathers lymph from the left upper limb; the left jugular trunk collects lymph from the left side of the head and neck; and the left bronchomediastinal trunk drains lymph primarily from the thoracic organs, including the lungs and the heart. These trunks empty their lymph into the thoracic duct, ensuring that the fluid is ultimately transported to the bloodstream via the subclavian vein. This anatomical arrangement is vital for the proper function of the lymphatic system and maintains fluid balance within the body. Understanding which trunks join the thoracic duct reinforces the importance of lymphatic drainage from various body regions and highlights the specialization of lymphatic pathways.