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Understanding Veins

The ongoing flow of blood from the heart to the body and back to the heart again is called circulation. Blood vessels carry blood throughout your body. Veins are the vessels that return blood to the heart.

Front view of body showing arteries, veins, heart, and closed circulation system.

Three Types of Veins

  • Superficial veins collect the blood just beneath the skin

  • Perforating veins carry blood from the superficial veins to the deep veins

  • Deep veins run through the muscles and carry 90 percent of the blood back to your heart

Section of skin and muscle showing deep, superficial, and perforating veins.

Anatomy of a vein

Veins have cup-like flaps called valves spaced along their inside walls. Valves open upward, so blood can move up the vein. Valves close to keep blood from falling back down the vein.

Cross section of muscle and vein showing open valve. Arrow shows blood moving up.Cross section of muscle and vein showing closed valve. Arrow shows blood moving up.

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