When a person looks at the body, they’ll note blue lines that seem to be right under the skin. Sometimes some of these protrude, especially if the person is warm. These are the superficial veins.
Veins are essentially part of the blood transport network. While arteries send blood out from the heart to oxygenate the organs and tissues, veins work to return this blood to the heart so that it can be sent back to the lungs to pick up more oxygen. The term superficial vein is a term used in contrast to deep vein. Deep veins are near an artery with a name that is similar, and usually can’t be seen on the body’s surface. They’re also often larger than superficial veins and more vital.
A superficial vein is not located near arteries bearing similar names, and though they are important to the body, they are not as vital as deep veins. In fact, if such a vein becomes too prominent, or becomes varicose, a term usually reserved for veins in the legs, people can have them removed via surgery named vein stripping. Since these veins are superficial, this is usually safe, as blood flow to the legs will still be adequate through deep veins. One of the biggest differences between a deep and a superficial vein is amount of blood carried; deep veins are responsible for transporting most of the blood, and superficial veins, though important, carry far less.
There are a few of these veins with which people may be familiar. The jugular vein, which actually does carry a high volume of blood, runs down the neck on either side, returning blood from the head to the heart. When people have blood tests, they frequently have blood drawn from a superficial vein on either arm called the median cubital vein, which may or may not be apparent in the underside of the arm, opposite the elbow.
Many people wonder why it is that veins seem to protrude after exertion, or sometimes even in hot weather. This is actually a function of these smaller blood vessels. If the body gets warm, the deep veins will send more blood to the superficial veins as a method of temperature control.
Some conditions can affect a superficial vein. Like deep veins, these close to the surface veins can get blood clots too, called superficial thrombophlebitis. This can be painful, but is usually not life threatening. The condition can cause inflammation of the vein, which can be felt, often as hard bump under the skin, and may require some special treatment with pain relievers and compression stockings (as it usually occurs in a leg). Superficial thrombophlebitis generally resolves in a few weeks, but doctors may want to check risk factors for developing deep vein thrombosis (DVT) too, which is much more serious.