What moves lymph through the lymphatic system?

The lymph is moved through the body in its own vessels making a one-way journey from the interstitial spaces to the subclavian veins at the base of the neck. Since the lymphatic system does not have a heart to pump it, its upward movement depends on the motions of the muscle and joint pumps.

Movement of blood in the circulatory system is through the pumping action of heart but the movement of lymph in the lymphatic system is due to the movement of muscles which push the lymph towards heart.

Explanation:

When the blood passes through the capillaries near tissues, some water along with some water soluble substances move out into the interstitial space. This fluid released out is called interstitial fluid or tissue fluid. This fluid is collected back and drained into the major veins by a network of vessels called the lymphatic system. The lymphatic system consists of:

Lymph capillaries

lymph vessels

lymph nodes

lymph ducts

Interstitial fluid enters the lymph capillaries as the wall is thin and porous. Once it enters the capillaries now it is called lymph. Lymph capillaries merge to join lymph vessels which further merge into ducts. These ducts drain the lymph into right and left subclavein veins. These veins drain into superior vena cava which connects to heart. In this way the tissue fluid formed by filtration of plasma out of blood capillaries is ultimately returned to the major veins.