What is the name of the enlarged sac to which the lumbar trunks and the intestinal trunk return lymp?

The lumbar trunk and intestinal trunk return lymp at the cisterna chyli. The cisterna chyli is also known as the receptaculum chyli. It is a normal anatomical structure seen as a saccular area of dilatation in the lymphatic channels that is located in the retrocrural space, usually to the immediate right of the abdominal aorta.

From a high concentration to a low concentration.