Varicose Vein Anatomy and Function for Patients

Whether you are a patient or someone just interested in learning about varicose veins and spider veins, you will probably find it necessary to have the definition of some medical words handy. Some words that you already know may have a slightly different meaning when they are used in a medical sense. For example, the word “leg” refers to the part of the lower extremity below the knee, not to the lower extremity from the hip to the foot.

Anatomical vein terminology

Anterior: the front of a body part.

Deep leg vein: the veins that are deep in the thigh and leg that carry blood back to the heart.

Deep fascia: connective tissue. This strong tissue is the white tissue that covers muscle.

Great saphenous vein – GSV – (long saphenous vein): a long vein that can be seen just in front of the anklebone. This vein travels along the inside of the leg and thigh (about one-half inch beneath the skin in the thigh) until it empties into the deep vein called the common femoral vein in the groin.

Leg: the part of the lower extremity below the knee.

Lesser saphenous vein – LSV:
 a superficial vein that starts at the outside of the foot and travels up the back of the calf where it empties into the deep vein (popliteal vein) in the crease of the knee.

Perforating vein: a vein that passes directly from a superficial vein to a deep vein.

Popliteal vein:
 the deep vein located behind the knee. The lesser saphenous vein originates from the popliteal vein.

Posterior: back of a body part.

Spider vein: a tiny varicose vein that may be blue or red color that does not protrude above the skin surface and frequently looks like a spider. The medical term for a spider vein is telangliectasia.

Superficial vein: any vein in the lower extremity above the deep fascia that covers the muscles of the thigh and leg.

Thigh: the part of the lower extremity above the knee.

Varicose vein: a bulging vein that protrudes past the skin surface and usually measures greater than one-fourth of an inch in diameter.

Anatomy of the Saphenous Veins

The great saphenous vein (GSV) carries blood from the leg and thigh up toward the heart. The GSV measures about 4mm-10mm (one-sixth inch to three-eighths inch) in diameter at the groin just before it empties into the common femoral vein at the saphenofemoral junction.

Note: In some books and anatomy drawings the great saphenous vein is called the long saphenous vein

Vein Terms for Function of Vein

Competent vein: blood flow occurs in the proper direction back to the heart. Also referred to as having no reflux or normal flow direction.

Incompetent vein: blood flows in the wrong direction. Also referred to as a vein that has reflux.

Reflux: blood that flows backward in the veins.

After the blood has been replenished with oxygen in the lungs, it is pumped to the body by the heart. Blood that is pumped to the lower extremities is pumped back to the heart partially by the action of the calf muscle pump. The blood returning from the lower extremities in the deep and superficial veins goes past a series of one-way valves. These valves stop the blood from flowing backwards in the veins.

The valves in the veins close just as blood begins to flow backwards. If the valves do not close properly, the blood falls backwards through the poorly closing or leaking valves. The veins downstream that are now unprotected by valves further upstream are exposed to the weight of an increasingly high column of blood. These downstream veins cannot endure the pressure of the column of blood and expand becoming snake-like in appearance. This causes the veins to bulge through the skin surface and become varicose veins.

What causes the valves in the veins to fail?

The vein wall may be congenitally weak or may enlarge because of exposure to hormones. This effect of hormones explains in part why varicose veins occur or worsen during pregnancy. The vein wall may expand (or dilate). The proper function of the valves depends upon how well the valve parts (valve cusps) come together to close. When the vein wall dilates, the valve cusps can no longer close properly.

During vigorous exercise of the lower extremities, the pressure of the blood in the veins rises to extreme levels of about 300 mm/hg. (This is about 2 to 2 times normal arterial blood pressure.) This high pressure further deteriorates already dilated and varicose veins worsening the varicose vein disorder.

What are the consequences of varicose veins?

Oxygen and nutrients are depleted from blood that pools in the varicose veins. The veins also do not tolerate high pressure well and begin to allow red blood cells and fluid to leak into the tissues of the leg. The fluid leak causes ankle swelling. The red blood cells in the tissues cause chronic inflammation and the skin becomes dark and discolored. The medical term for the dark discoloration is hyperpigmentation. When the skin and the fat under the skin are inflamed for years, the tissues become woody and firm. The medical term for this woody, hard tissue is lipodermosclerosis.

Another possible consequence of untreated varicose veins is spontaneous bleeding from the varicose veins. As the skin over the veins becomes thin, eventually the vein can be exposed to the outside world and be easily injured by clothing, bedding, etc. The blood loss can be significant and is painless.

How are blood clots formed in varicose veins?

The blood flow in varicose veins is slow enough to encourage blood to coagulate. The medical term, superficial thrombophlebitis, refers to the occurrence of blood clots in superficial veins. Superficial thrombophlebitis rarely causes death or a blood clot that travels to the lungs. However, progression of a superficial phlebitis to involve the deep system may have fatal consequences.

What are the effects of varicose vein treatment on blood flow?

What are the effects of varicose vein treatment on blood flow? The treatment of varicose veins by any means either removes the vein or prevents the flow of blood through the veins. Patients are frequently concerned that the loss of the varicose veins will have a negative effect on their circulation. They ask, “How will the blood get back to my heart if these veins are gone?”

The answer is that varicose veins do not help the circulation; they actually harm the circulation. Their removal or the treatment improves the circulation by removing the veins where blood stagnates and actually harms the circulation. Thus blood flow is actually improved by allowing blood to pass through the remaining normally functioning veins.

What are the other types of varicose veins?

Varicosity occurs in veins of various sizes. Small varicose veins that do not bulge through the skin are called reticular veins. Extremely small varicose veins that are the size of a tiny injection needle are known as spider veins. They are all faulty (incompetent) because they allow the blood to flow backwards.

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Content reviewed and updated on August 3, 2013.