Communicating veins are

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

s that communicate two different points of the venous system. They can communicate the

great saphenous vein The great saphenous vein (GSV, alternately "long saphenous vein"; ) is a large, subcutaneous, superficial vein of the leg. It is the longest vein in the body, running along the length of the lower limb, returning blood from the foot, leg and thig ...

with the

small saphenous vein The small saphenous vein (also short saphenous vein or lesser saphenous vein) is a relatively large superficial vein of the posterior leg. Structure The origin of the small saphenous vein, (SSV) is where the dorsal vein from the fifth digit (small ...

, (for example the

Giacomini vein The Giacomini vein, or cranial extension of the small saphenous vein is a communicating vein between the great saphenous vein (GSV) and the small saphenous vein (SSV). It is named after the Italian anatomist Carlo Giacomini (1840–1898). The G ...

) or the superficial venous system with the deep one. In this case they are called

perforator vein Perforator veins are so called because they perforate the deep fascia of muscles, to connect the superficial veins to the deep veins where they drain. Perforator veins play an essential role in maintaining normal blood draining. They have valves ...

s and have a very important role in the venous system hemodynamics.

References

Veins {{circulatory-stub