Popliteal fossaThe popliteal vein is a deep vein that drains the leg. The sciatic nerve runs down the posterior surface of the leg, and its largest branch, the tibial nerve is the most superficial structure of the popliteal fossa, which is a diamond-shaped fossa that lies at the posterior surface of the knee. The biceps femoris defines the popliteal fossa proximolaterally, and the semimembranosus and semitendinosus muscles define its proximomedial border. The two heads of the gastrocnemius muscle form the inferior borders, medially and laterally.
The popliteal vein is formed by the confluence of the deep veins of the leg, i.e. the posterior tibial, anterior tibial and common fibular veins. It also receives venous blood from the superficial vein of the lateral leg, i.e. the short saphenous vein. The short saphenous vein pierces the deep fascia of the leg, and enters the popliteal fossa by passing through the two heads of the gastrocnemius.
The popliteal vein then ascends and passes through the adductor hiatus (an opening formed between the two insertions of the adductor magnus muscle) to become the femoral vein, which passes superiorly and runs in the femoral triangle medial to the femoral artery, which is itself medial to the femoral nerve. The femoral nerve runs underneath the inguinal ligament, and provides motor innervation to the anterior compartment of the thigh.
Popliteal vein aneurysm: Popliteal vein aneurysms are rare, and do not commonly present clinically. Surgical repair is indicated if it is causing symptoms, such as:
- deep vein thrombosis
- pulmonary embolisms
Deep vein thrombosis: The deep veins of the lower limb are the most vulnerable to this condition, which rarely presents in the upper limb. Any patient that has prothrombotic risk factors is at risk of deep vein thrombosis. Some of these factors include:
- lack of mobility
- use of oestrogen contraceptive pills
- recent surgery