Veins under the skin
Most deep veins run beside an artery of the same name. A second set runs in the fat under the skin with no artery beside it. These are the veins that show blue through the skin and are used for blood tests and drips.
In the arm the cephalic vein climbs the thumb side and the basilic vein the side of the little finger, joined at the elbow by the median cubital vein. In the leg the great saphenous vein, the longest in the body, runs from the inner ankle to the groin, and the small saphenous climbs the back of the calf.
The superficial veins of the arm: the cephalic and basilic veins, joined in front of the elbow by the median cubital vein (vena mediana cubiti), Gray's Anatomy, 1918, figure 574Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray574.png)
The great (internal) saphenous vein joining the femoral vein in the groin, with the small superficial veins of the lower abdomen, Gray's Anatomy, 1918, figure 584Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray584.png)
Valves inside them, and inside the perforating veins that join them to the deep veins, let blood pass only upwards and inwards. When these valves fail, blood pools in the superficial veins of the leg and they swell into varicose veins.
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapters on the elbow and forearm and on the leg.
- Arthur Guyton and John Hall, Textbook of Medical Physiology, 13th ed. (2016), ch. 15.
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