Below is a basic outline of the anatomy and function of the veins and what constitutes venous incompetence. Be aware however that there are numerous anatomical variations.
The veins contain a series of valves along their course, preventing retrograde flow back down the leg. These valves operate like two plastic doors opening up the leg. If back pressure is applied, they swing closed, pushing against each other, blocking reverse flow down the leg.
If functioning normally, it is a competent valve. If blood is able to pass backwards though the valve, it is deemed incompetent.
Depending on the extent of incompetence, this backflow will dilate the supple superficial veins making them tortuous and dilated(varicose veins).
Familial factors with ‘lax’ veins. These distend slightly allowing the valve leaflets to no longer oppose each other.
Injury or thrombosis. Both of these can lead to adherance of valve leaflets to the vein wall, rendering the valve useless.
The Deep Veins
Are the primary route for returning blood to the heart. They collect the venous blood from all the draining muscular and superficial veins.
In the lower limb the deep veins are: (from groin to ankle)
- Common Femoral Vein (CFV)
- Superficial Femoral Vein (SFV)- also called just the Femoral Vein.
- Popliteal vein (POPV)
- Anterior tibial (ATV)
- Posterior tibial (PTV
- Peroneal veins (Per V)
The latter 3 are calf veins that generally run in pairs (venous commantantes)
The Superficial Veins
There are 2 main superficial veins draining the subcutaneous tissue of the lower leg:
The Great Saphenous vein (GSV) runs from the medial malleolus, up the medial aspect of the leg, draining into the CFV at the groin as the Sapheno-femoral junction (SFJ).
The Short Saphenous vein (SSV) runs up the posterior midline of the calf. It may drain into the proximal POPV above the knee crease as the Sapheno-Popliteal junction (SPJ). Commonly however, it may continue up the posterior thigh as the Giacomini vein. This will terminate either into the mid/distal SFV or ascend to drain into the proximal LSV.
Incompetence of the SFJ and SPJ are the two primary sources of varicose veins.