Leg Vein Anatomy
Veins – Function and Categorization
Veins (from the Latin vena) are blood vessels that carry blood towards the heart. Arteries on the other hand, carry blood away from the heart, completing the circulatory system. A vein can range in size from 1 millimeter to 1.5 centimeters in diameter. With a few exceptions, like the veins carrying blood from the lungs to the heart, veins that return blood from the body carry oxygen poor (deoxygenated) blood. Veins can be categorized into superficial and deep veins.
Venous Structure of Legs
The venous structure of the lower limb may be envisioned as similar to an upside-down tree, with blood originating in superficial venous capillaries and moving upward and inward through increasingly larger veins on its way towards the heart. This task is accomplished through two vein systems that run parallel to each other. One is the deep vein system that runs within the muscles of the legs, and the other is the superficial vein system that runs in the fat layer between the muscle compartments and the skin. Deep veins lead to the vena cava, the largest vein in the body connected directly to the heart. The superficial veins drain into the deep veins at some major “collection points” where the Great and Lesser Sahenous veins drain the blood at the groin and the back of the knee respectively, or throughout the legs via smaller and short bridging veins called perforator veins. Major perforators have been identified and given names: Hunter, Dodd, and Boyd or Cockette are a few examples. It is estimated that on each leg there are approximately 90–150 perforators. Perforator veins are also known as communicating veins because they transport the blood directly from the superficial veins to the deep veins, connecting two parallel systems: the superficial venous system, and the deep venous system, somewhat like the rungs of a ladder connecting the two side rails.
THE PRINCIPLE SUPERFICIAL AND DEEP VEINS OF THE LEG
Superficial veins include innumerable venous tributaries known as collecting veins, as well the truncal veins and their tributaries. The truncal veins (similar to the trunk of the upside-down tree mentioned earlier) are made up of the Great Saphenous Veins (GSV), and the Small Saphenous Vein (SSV), also known as Lesser Saphenous Vein or (LSV ).
The Great Saphenous Vein is the longest vein in the body; it runs from inside of the ankle, to the inside of the knee, and up to the groin where it joins the femoral vein (saphenofemoral junction). This vein derives its name from the word safina, meaning “hidden”, because it is “hidden” under a layer of connective tissue. The Short or Lesser Saphenous Vein, on the other hand, runs in the back of the calf from the level of the ankle to the back of the knee where it drains into the deep venous system (saphenopopliteal junction). Large bulging leg veins are often tributaries of either saphenous veins.
The leg veins that deteriorate the most as people age are the superficial veins and perforator veins. The very superficial and visible branches are known as varicose, reticular, and spider veins. The formation of varicose veins in the ‘deep’ veins is relatively rare because they are supported by the surrounding muscles. Superficial veins on the other hand, have less muscle support; accordingly, congestion in these veins is much more likely to result in bulgy, dilated and twisted varicosities.