Veins of the Lower Limb
The lower limb consists of two main types of veins:
- Superficial veins
- Deep veins
The superficial veins are located within the subcutaneous tissue whilst the deep veins are found deep to the deep fascia. The deep veins accompany the major arteries and their branches and are usually paired. They are located within a vascular sheath with the corresponding artery, which helps compress and move blood within the veins. Both types of veins contain venous valves, to prevent reflux of blood distally, but they are more numerous in the deep veins. They also contain tributaries, other veins which drain into them. This article will discuss the anatomy and tributaries of the veins of the lower limb in detail, followed by any related clinical notes.
Superficial Veins of the Lower Limb
There are two main superficial veins of the lower limb, referred to as the:
- Long saphenous vein
- Short saphenous vein
Long Saphenous Vein
The long saphenous vein is also referred to as the great saphenous vein and is the longest vein in the human body. It is a continuation of the medial marginal vein of the foot and ends in the femoral vein, distal to the inguinal ligament.
It ascends superficial to the medial malleolus, before crossing the distal third of the tibia anteroposteriorly. It passes behind the medial tibial and femoral condyles before ascending up the medial aspect of the thigh and passing through the saphenous opening, an aperture in the fascia lata of the thigh. It opens into the femoral vein 2.5 – 3.5 cm inferolateral to the pubic tubercle. The long saphenous vein is accompanied by branches of the medial femoral cutaneous nerve throughout its course in the thigh. It contains 10-20 venous valves, which are more numerous within the leg.
The long saphenous vein has many connections with the short saphenous vein and the deep veins of the lower limb via perforating veins. Just distal to the knee, the long saphenous vein receives three main tributaries:
- From the front of the leg
- From the tibial malleolar region
- From the calf
In the thigh, the long saphenous vein usually has six main tributaries:
- Posteromedial vein of the thigh
- Anterior femoral cutaneous vein
- Superficial epigastric vein
- Superficial circumflex iliac vein
- Superficial external pudendal vein
- Deep external pudendal vein
The posteromedial vein of the thigh, sometimes referred to as the accessory vein of the thigh, drains the superficial aspect of the posteromedial region of the thigh. The anterior femoral cutaneous vein is a continuation of anterior veins in the distal thigh and crosses the femoral triangle before opening into the long saphenous vein. The superficial epigastric vein and superficial circumflex iliac vein drain the inferior abdominal wall and open into the long saphenous vein as it traverses the saphenous opening. The superficial external pudendal vein also opens into the long saphenous vein at this point and it drains part of the scrotum or labia. The deep external pudendal vein also joins the long saphenous vein at the saphenous opening.
Short Saphenous Vein
The short saphenous vein, also referred to as the small saphenous vein, is a continuation of the lateral marginal vein. It passes lateral to the calcaneal tendon and ascends between the superficial and deep fascia in the distal third of the calf. At the midline of the calf, it penetrates the deep fascia before ascending superficial to the gastrocnemius muscle. At the junction of the intermediate and proximal thirds of the calf, the short saphenous vein emerges above the deep fascia before passing between the heads of the gastrocnemius muscle. It terminates in the popliteal vein within the popliteal fossa, 3- 7.5 cm above the knee joint.
The short saphenous vein has 7-13 valves and lies near the sural nerve within the leg. On the dorsum of the foot, deep veins drain into the short saphenous vein and within the leg, it receives many cutaneous tributaries. It has many branches, which communicate with the long saphenous vein.
Deep Veins of the Lower Limb
The deep veins of the lower limb can be separated into four main groups, according to their location:
- Veins of the foot
- Veins of the leg
- Vein of the knee
- Veins of the thigh
Veins of the Foot
The foot consists of two main types of deep veins: plantar veins, which drain the plantar surface or underside of the foot and dorsal veins, which drain the dorsal or upper surface of the foot. Venous plexuses within the plantar regions of the toes join to form plantar digital veins. These veins connect with their dorsal counterparts, the dorsal digital veins, to form four plantar metatarsal veins. These veins run proximally within the intermetatarsal spaces and then continue on to form the deep plantar venous arch. Medial and lateral plantar veins arise from this arch.
A dorsal venous arch is also present and is formed by the dorsal metatarsal veins, which are also formed by the dorsal and plantar digital veins.
Veins of the Leg
The anterior tibial veins are formed by the venae comitantes, or companion veins, of the dorsalis pedis artery.
The posterior tibial veins are formed by the medial and lateral plantar veins and accompany the posterior tibial artery. Veins from the calf muscles drain into posterior tibial veins. They also receive connections from the superficial veins and the fibular veins.
The fibular veins are also formed by the medial and lateral plantar veins and run with the fibular artery. They receive tributaries from superficial veins and veins draining the soleus muscle.
Vein of the Knee
The popliteal vein is located within the popliteal fossa and pierces the adductor magnus muscle, where it becomes the femoral vein. Distally it is medial to the popliteal artery. Between the two heads of the gastrocnemius muscle it is superficial to it and proximally it is posterolateral to it.
The popliteal vein usually has 4 or 5 valves and many tributaries. All of the three main veins of the leg drain into it, as well as the short saphenous vein and two muscular veins from each head of the gastrocnemius muscle.
Veins of the Thigh
The femoral vein is a continuation of the popliteal vein and accompanies the femoral artery. It begins at the opening of the adductor magnus muscle and ends posterior to the inguinal ligament as the external iliac vein.
Its relationship to the femoral artery is variable. Within the distal adductor canal, it is located posterolateral to the artery, whilst in the proximal canal and in the apex of the femoral triangle, it lies posterior to the artery. Within the base of the femoral triangle, it is found medial to the femoral artery. It is contained within the middle compartment of the femoral sheath and usually has four or five valves.
Tributaries of the femoral vein include:
- the medial circumflex vein
- lateral circumflex vein
- long saphenous vein
- profunda femoris vein, which drains 4-12 cm distal to the inguinal ligament.
The profunda femoris vein, also referred to as the deep vein of the thigh, is located superficial to the profunda femoris artery. Veins accompanying the perforating branches of the profunda femoris artery drain the thigh muscles and empty into the profunda femoris vein. The medial and lateral circumflex veins are sometimes tributaries of the profunda femoris vein.
Varicose veins are common in the long saphenous vein and its tributaries and appear due to venous insufficiency. This occurs when the valves become incompetent, resulting in retrograde flow of blood within the veins. This results in dilated and tortuous veins. Symptoms include:
- exercise intolerance
- pruritis (itch)
Treatment involves injection of a sclerosing agent, which breaks down the endothelial wall of the vein. Following treatment and for prevention of further varicose veins, compression stockings are recommended.
Venous thromboembolism (VTE) is a blood clotting disease that can manifest as deep vein thrombosis (DVT) or a pulmonary embolism (PE). Three factors, known as Virchow’s triad, are important in the development of a venous thrombosis. They are:
- Venous stasis
- Activation of blood coagulation
- Vein damage
DVTs are common in the deep veins of the lower limb and symptoms include oedema, tenderness and erythema (redness). Diagnosis of a DVT involves the utilisation of the Wells Score, which predicts the probability of a DVT. Points are assigned for symptoms such as recent surgery, tenderness and oedema, among others, and a score greater than or equal to 3 suggests a high probability of a DVT. Treatment involves anticoagulation with pharmocotherapeutic agents such as heparin, warfarin and factor Xa inhibitors. Compression stockings are used as a preventative strategy.
Pulmonary embolism (PE) is a very serious complication of DVT in the lower limb, which can lead to death if a main pulmonary artery is obstructed. It occurs when a thrombus within a deep vein embolises and travels to the lungs via the inferior vena cava and the right atrium. Classical symptoms include chest pain and shortness of breath. However, PE may present atypically with symptoms such as seizures, syncope (fainting), haemoptysis (coughing up blood) and fever. Treatment with anticoagulation is essential and may also involve thrombolytic therapy with agents such as alteplase.
Grafting for Bypass
The long saphenous vein is commonly harvested in order to bypass an obstructed coronary artery. The bypass surgery is referred to as a coronary artery bypass and once harvested the vein is referred to as a graft. It is commonly used as it is easily accessible and its removal is not problematic due to other collateral circulations in the lower limb. Before the vein is used as a bypass it is reversed, so the valves do not occlude blood flow in the graft.