Venous AnatomyCHAPTER 1

Knowledge of venous anatomy is essential for diagnosis and treatment of venous disorders of the lower limb. Venous anatomy was largely ignored in earlier anatomy textbooks, and its importance underappreciated. However, with increase in interest in venous disease and advent of newer imaging methods, much information has been gathered in this field. The unique anatomy in the lower limbs enables veins to act both as a reservoir of excess blood as well as a conduit for the return of blood to the heart.

In the skin, capillaries drain into a subpapillary venous plexus which drains into a deeper reticular plexus at the dermal subcutaneous junction. Vertically oriented veins connect the reticular plexus to the superficial veins.

This begins at the medial end of the dorsal venous arch and ascends 2.5–3 cm anterior to the medial malleolus. It crosses the distal third of the medial surface of the tibia obliquely to its medial border. It ascends a little behind the medial border and crosses the knee posteromedial to the medial tibial and femoral condyles. It runs on the medial side of the thigh and enters the fossa ovalis 3 cm below and lateral to the pubic tubercle. At this point, it drains into the femoral vein at the saphenofemoral junction (SFJ). The surface anatomy is marked from this point to the adductor tubercle of the femur. The SFJ however is highly variable and the surface marking is not reliable (Fig. 1.3).³

In the calf, the great saphenous vein (GSV) has two main tributaries, the anterior and posterior arch veins.

The posterior arch vein, also called Leonardo's vein (first depicted in Da Vinci's drawing) drains a fine network below the medial ankle, ascends on medial aspect of the lower half of the leg and joins the GSV just distal to the knee. The Cockett's perforators connect the posterior arch vein to the posterior tibial veins as shall be seen later. There are several other variable, unnamed communications with the SSV.

Just before the SFJ, the GSV receives the superficial external pudendal, superficial external iliac, and the superficial inferior epigastric veins. A little more distally is the drainage of the medial and lateral accessory saphenous veins. Various attempts have been made to classify the confluence of veins at the SFJ, but none are reliable due to the high variability of this confluence. Most commonly what has been described is a venous star, as shown in Figure 1.4, involving the five main tributaries. But there can be any number of patterns of the tributaries draining into each other, or separately into the femoral vein.⁵4

It begins on the lateral aspect of the dorsal venous arch, runs behind the lateral malleolus and ascends lateral to the Achilles tendon. In the upper third of the leg, it pierces the deep fascia between the two heads of the gastrocnemius and empties into the popliteal vein in the proximal popliteal fossa at the saphenopopliteal junction (SPJ). In a third of patients, it empties high into the femoral vein or the GSV. Its surface marking is from a point midway between the bottom of the lateral malleolus and the tendoachilles to the midpoint of the knee joint line.²

There are several communicating branches between the SSV and the GSV. In 15% of patients, there is a large communicating vein named after Giacomini which connects the proximal part of the SSV to the GSV. There are other small communications between the saphenous veins around the knee (Fig. 1.5).⁶

The termination of the SPJ is highly variable. A short time ago, a universally accepted classification for the SPJ was established. Type A is the classical SPJ. Type B is when the SSV empties into the SPJ with another cranial extension into the GSV or SFJ. Type C is when there is no SPJ, but the vein empties higher up (Fig. 1.6).⁷5

In the superficial veins, bicuspid valves exist which direct blood flow towards the heart. There are larger valves at termination of venous trunks with 6strong cusps and sinusoidal dilatation of the vein wall. The GSV usually has 6–14 valves, which are more numerous in the leg than the thigh. One valve called the preterminal valve is present as it pierces the cribriform fascia. The terminal valve is present at its junction with the femoral vein. The SSV has 4–13 valves which are more closely spaced, with the highest valve at the termination of the SSV. Valves in communicating tributaries direct blood from the SSV to the GSV.⁸

The deep plantar arch collects blood from the toes and metatarsum. This then forms the medial and lateral plantar veins, which form the posterior tibial vein behind the medial ankle. The major dorsal deep veins (dorsalis pedis) form the anterior tibial veins.⁹

These are thin walled venous reservoirs in the calf muscles, which contract during ambulation. They act as a peripheral muscle pump to aid in venous return against gravity. The soleus is rich with sinuses while the gastrocnemius has few. These sinuses are filled by superficial veins via indirect perforators and via muscular veins. They drain into deep veins via soleus and gastrocnemius veins. The sinuses themselves have no valves, but their draining veins do. These valves are vital for the efficiency of the peripheral muscle pump (Fig. 1.8).¹⁰

Perforating veins are either direct in which case they drain into deep veins, or indirect where they drain into deep veins via calf muscle sinuses. Small 8communicating branches often connect perforators to one another. There perforators usually have one to three valves which direct blood flow from superficial to deep. The number of perforating veins has been variably reported in various studies, with as many as 150 been reported.

The foot usually has around 10 perforators. One large one in the first web space connects the superficial venous arch to the dorsalis pedis. On the medial aspect, perforators connect the GSV to the dorsalis pedis. On the lateral aspect, perforators connect the SSV to the lateral plantar deep vein. The ankle perforators were previously named after May and Kuster.⁹

The medial calf perforators are clinically the most significant. They were formerly named after Cockett into three groups; Cockett I (behind malleolus), Cockett II (7–9 cm from tip of medial malleolus) and Cockett III (10–12 cm from malleolus). These are all located 2–4 cm from the medial edge of the tibia and average 7–8 in number. These connect the GSV and posterior arch vein with the posterior tibial veins. In the upper half of the leg, perforators are located more closely to the tibia and are called paratibial perforators. They are usually seen in three groups; at distances of 18–22, 23–27 and 28–32 cm from the medial malleolus. The 18–22 cm group was also called the 24 cm perforator due to its distance from the sole. These perforators drain the GSV, and its tributaries into the posterior tibial veins. Just distal to the knee, there is another consistent set of perforators formerly called Boyd's perforators which connect the GSV to the popliteal veins.¹²

On the lateral calf, the peroneal perforators connect the SSV to the peroneal vein. Named ones include the Bassi's perforator at 5–7 cm from lateral malleolus and the 12 cm perforator at 12–14 cm from the lateral malleolus. More proximally, perforators are usually indirect. On the anterior calf, the perforators of note include the premalleolar and midcrural ones which drain GSV into anterior tibial vein.¹³

In the thigh, direct perforators are less frequent. They include the Dodd's and Hunterian perforators to the popliteal and superficial femoral respectively. Several indirect perforators to the muscular veins exist (Fig. 1.9).¹⁴

The vein wall is made up of three layers; the intima, media and adventitia. The intima consists of a single layer of endothelial cells lying on connective tissue. Valves are made up of connective tissue with intima on both sides.10

The media is made up of smooth muscle cells and connective tissue. Larger veins have more smooth muscle and are resistant to varicosity. Smaller tributaries have less muscle and are more prone for varicosity. The adventitia is poorly demarcated and contains vessels, nerves and lymphatics.¹⁵

The saphenous nerve descends with the superficial femoral artery, deep to the sartorius. It gives an infrapatellar branch to supply the skin medial to the knee. The main nerve pierces the fascia lata above the knee and becomes superficial between the gracilis and sartorius, at which point it is deep and posterior to the GSV. Below this point, it becomes more superficial and anterior, and is eventually juxtaposed with the GSV, around 2–3 cm below and medial to the tibial tuberosity. The nerve then travels close to the GSV, which makes vein removal almost impossible without nerve injury. Eventually it terminates by supply skin over medial leg and foot.

This nerve arises from the tibial nerve in the popliteal fossa, descends in the posterior leg to the back of the lateral malleolus. It lies on the lateral head of the 11gastrocnemius and then lies in the groove between the two heads, lateral to the SSV. It usually pierces the deep fascia with the SSV and then courses close to the SSV. It terminates by supplying the skin over posterior half and lateral foot.¹⁷

In conclusion, venous anatomy of the lower limb is one of the most variable and unpredictable in the entire body. A thorough knowledge of the most common patterns enable us to identify variations when they arise; thereby ensuring adequate identification and treatment of various venous disorders.