This video illustrates normal lymphatic anatomy and flow. The lymphatic system plays a crucial role in immune function and in the delivery of vital nutrients to the body. Functioning almost like a sponge, the lymphatic system absorbs excess lymph fluid from the body’s organs and returns it to the blood stream. In a healthy body, the lymphatic channels from the liver and mesentery drain toward the thoracic duct, which is the main lymphatic vessel responsible for lymph drainage. In most people, the thoracic duct drains into the subclavian vein on the left side.