The saphenous vein is a major part of the superficial venous system in the leg, responsible for returning blood to the heart. This system consists of two primary vessels in each leg: the Great Saphenous Vein (GSV) and the Small Saphenous Vein (SSV). They are located just beneath the skin’s surface. Understanding their structure and function is important because they are frequently involved in common circulatory issues and are sometimes utilized in significant medical procedures.
Anatomical Structure and Location
The Great Saphenous Vein (GSV) is the longest vein in the human body, extending from the foot up to the groin area. It originates from the dorsal venous arch on the top of the foot near the medial (inner) ankle. The GSV travels superficially along the entire inner side of the leg and thigh.
The vein’s upward course ends in the upper thigh, where it connects with the femoral vein, a major deep vein. This junction, known as the saphenofemoral junction, is located near the groin. Throughout its path, the GSV collects deoxygenated blood from numerous smaller, superficial branches.
The Small Saphenous Vein (SSV) begins on the lateral (outer) side of the dorsal venous arch of the foot. It runs upward along the back of the calf, following the Achilles tendon and passing behind the knee. The SSV ends by draining into the popliteal vein, which is situated in the popliteal fossa, the depression behind the knee.
The Role of Saphenous Veins in Circulation
The primary function of the saphenous veins is to collect oxygen-poor blood from the superficial tissues of the feet and legs and return it toward the heart. This blood is channeled into the deeper venous system, which handles the bulk of the blood return from the limbs. The GSV empties into the femoral vein, and the SSV drains into the popliteal vein, effectively transferring the superficial blood flow to the deep system.
Moving blood upward against gravity is achieved through the action of one-way venous valves located inside the saphenous veins. These valves open to allow blood to flow toward the heart and immediately close to prevent backward flow, or reflux. The movement of surrounding muscles, particularly the calf muscles, compresses the veins. This muscle action acts as a pump, propelling the blood past the closed valves and maintaining healthy venous return.
Common Issues Affecting the Saphenous Vein
The most frequent problem involving the saphenous veins is Chronic Venous Insufficiency (CVI), a condition where the one-way valves become weakened or damaged. When these valves fail to close correctly, blood flows backward and pools in the lower leg veins, a phenomenon called venous reflux. This pooling increases pressure within the veins, leading to stretching and enlargement that manifests visibly as varicose veins. The GSV is the most common site for this insufficiency, but the SSV can also be affected.
CVI can cause symptoms such as leg swelling, a feeling of heaviness, aching, and skin changes near the ankles. Another issue that can affect the saphenous veins is superficial thrombophlebitis, which involves the formation of a blood clot and subsequent inflammation in the vein close to the skin’s surface.
Therapeutic Uses in Medicine
The Great Saphenous Vein is frequently used in Coronary Artery Bypass Grafting (CABG), commonly known as heart bypass surgery. In this surgery, a segment of the GSV is harvested from the leg and used to create a new path around a blocked coronary artery in the heart. The GSV is a preferred choice for this graft because of its considerable length and accessibility.
Because the GSV is a superficial vein, its removal generally does not impair circulation in the leg, as the body easily reroutes blood flow through the remaining deep venous network. When the harvested vein is connected to the arterial system, surgeons must address the vein’s internal valves to ensure blood can flow freely in the new graft, either by reversing the segment or destroying the valves. Although arterial grafts are generally preferred for their better long-term durability, the saphenous vein remains a commonly used and highly versatile conduit, especially when multiple bypasses are needed.