Ventrolateral view, left side

Ventrolateral view, left side

  Ventrolateral view, left side

The thoracic duct (quack) is part of the lymphatic system.  It is often recognized because it looks like a string of beads.  The constrictions in its walls are where the one way (semilunar) valves are.  We find the thoracic duct dorsal to the descending aorta.  It empties its contents into the brachiocephalic or subclavian vein on the left side of a human.  Since there is no dedicated pump to create pressure gradients to move the lymphatic fluid, we rely on the skeletal muscle pump and the one way valves to direct the flow though the lymphatic channels.