Reset Help Thoracic duct Body region drained by thoracic duct Right lymphatic duct Cisterna chyli Body region drained by right lymphatic duct Thoracic duct emptying into left subclavian vein
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Explanation of the Lymphatic Drainage System
This diagram illustrates the major pathways of the human lymphatic system, which is responsible for returning excess interstitial fluid, now called lymph, back to the bloodstream. The system’s drainage is asymmetrical, divided between two primary collecting vessels.
The largest lymphatic vessel is the thoracic duct. It begins in the abdomen as a dilated sac called the cisterna chyli, which collects lymph from the lower body and the intestines. From the cisterna chyli, the thoracic duct ascends through the thoracic cavity, collecting lymph from the left side of the body and the entire region below the ribs. The schematic on the right highlights this vast body region drained by the thoracic duct, which constitutes about 75% of the body. The journey of the lymph concludes as the thoracic duct empties into the left subclavian vein, returning the fluid to the circulatory system at the junction of the left subclavian and internal jugular veins.
The remaining 25% of the body is drained by the much smaller right lymphatic duct. This vessel is responsible for collecting lymph from the upper right quadrant of the body. As shown in the schematic, the body region drained by the right lymphatic duct includes the right side of the head and neck, the right arm, and the right side of the thorax. The right lymphatic duct then empties its collected lymph into the bloodstream at the junction of the right subclavian and right internal jugular veins. This division ensures that all fluid that leaks from blood capillaries into the body’s tissues is efficiently collected, filtered through lymph nodes, and returned to the blood, maintaining fluid balance and supporting the immune system.
