Trace the pathway of lymph from the lower limb to the venous system.

• A. Lymphatic capillaries in leg -> afferent lymphatics -> regional nodes (popliteal, inguinal) -> efferent vessels -> lymphatic trunks -> cisterna chyli -> thoracic duct -> left subclavian vein
• B. Capillaries to thoracic duct to left subclavian vein
• C. Veins to cisterna chyli to thoracic duct to right subclavian vein
• D. Arteries to lymph nodes to thoracic duct to inferior vena cava

Answer: (A)

The main idea here is how lymphatic fluid collected from the lower limb travels back into the bloodstream through a progressive, node-filtered route that ends at the left venous angle. Lymph begins in the lymphatic capillaries of the leg and flows into afferent lymphatics that bring it to regional nodes, specifically the popliteal and inguinal nodes. In the nodes, lymph is filtered before it exits via efferent vessels and continues into lymphatic trunks, such as the lumbar trunks, which converge to form the cisterna chyli in the abdomen. From there, the lymphatic fluid enters the thoracic duct, which ascends through the thorax and drains into the left subclavian vein at its junction with the left internal jugular vein. This pathway—leg capillaries, regional nodes, efferent vessels, trunks, cisterna chyli, thoracic duct, and finally left subclavian vein—accurately reflects how lymph from the lower limb returns to the venous system. The right-side drainage route or shortcuts via arteries or direct venous connections aren’t consistent with how lymph circulates, which is why the described sequence is the correct one.