Popliteal Fossa

fossa poplitea

The popliteal fossa is the diamond-shaped space posterior to the knee joint, bounded superolaterally by biceps femoris, superomedially by semimembranosus and semitendinosus, and inferiorly by the two heads of gastrocnemius. Its floor is the popliteal surface of the femur, the posterior knee capsule, and the popliteus muscle. The popliteal fossa contains the popliteal artery and vein (deepest to superficial), the tibial nerve, and the common peroneal nerve along the biceps tendon.

Region: Knee

Clinical Relevance

Clinical Notes

The popliteal fossa is the site of Baker cysts (popliteal cysts from posterior knee joint bulging between the medial gastrocnemius and semimembranosus bursa), popliteal artery aneurysms, and popliteal nerve entrapments. The popliteal artery's deep position adjacent to the femur and capsule makes it vulnerable in posterior knee dislocation. Popliteal nerve blocks for knee surgery target the tibial and common peroneal nerves in this fossa 7-8 cm above the popliteal crease.

Pathology

Common Injuries & Conditions

Popliteal Artery Injury in Knee Dislocation

Posterior knee dislocation stretches the popliteal artery over the posterior femoral condyles, producing intimal tear, thrombosis, or transection; vascular injury occurs in 25-40% of knee dislocations with risk of limb loss if revascularisation is delayed beyond 6 hours, mandating ABI assessment and CT angiography in all knee dislocations.