Up to 60% of the adult population will develop varicose veins and/or smaller visible veins called "spider" veins. What causes varicose and spider veins is just beginning to be understood. It is now believed that a type of injury to vein walls and venous valves is the problem. This injury is actually an acquired inflammation of the vein walls and valves. This is in turn exacerbated by other factors such as heredity, obesity, female gender, pregnancy, hormones, standing occupation and aging. Genetics plays a big role in the development of varicose veins. Although it's not possible to change the genes your parents gave you, many other factors also affect the formation and severity of varicose veins.
To understand why the different lifestyle factors make such an impact, it's important to have a basic understanding of how veins work. The main purpose of leg veins is to return blood up the legs to the heart. The blood is pumped up the legs by muscle contraction and breathing. So, when you walk or move, the venous blood moves. And when you stand still, so does the blood.
The weight of all the blood in your legs is very heavy - so heavy, in fact, you would think it would drain down to your feet when you stand still. The veins prevent this from happening. Hundreds of small valves within the leg veins shut when you stand still. These valves keep the blood in place and stop it from running back down to your feet, which appears as swelling in the feet if you are developing venous insufficiency. When you start to walk again, the valves open up and the blood is pumped toward the heart.
Different Types of Vein Terms/Names Deep Veins are are located deep in the leg between muscle and fascia (tough fibrous tissue). They are responsible for returning 90-95% of the venous blood back to the heart. Perforating Veins link the deep and superficial veins together. Superficial Veins are usually affected by varicosities because they have little external support like the deep veins. These veins are visible from the skin when varicose. They drain the blood from the skin and are also responsible for blood storage. When these veins become varicose they can appear engorged and distended. This group also includes reticular veins and 'spider' veins. Reticular veins are small blue veins often seen through the skin. These are often the cause of spider veins, which are the tiniest blue purple veins seen in the skin.