While the circulatory system relies on the continuous pump of the heart, the lymphatic system relies on other factors to achieve continuous pumping. They are:

• Gravity
• Changes in pressure within the tissues that push the lymph towards the vessels.
• Smooth muscles in the walls of the larger lymphatic pre-collecting and collecting vessels, which contract and push the lymph centrally with the help of valves.
• Contraction of surrounding structures such as arteries and muscles compressing lymphatic vessels and pushing lymph centrally.

Within the lymphatic vessels, valves and muscles help move the fluid to the larger collecting vessels and then to the lymph nodes.