Popliteal Plexus

plexus popliteus

The popliteal plexus is a network of sympathetic and sensory nerve fibres surrounding the popliteal artery, formed by contributions from the tibial and common peroneal nerves. It provides vasomotor innervation to the popliteal vessels and sensory innervation to the posterior knee capsule and synovium.

Anatomical Data

Course & Distribution

Origin	Articular branches of the tibial nerve and the posterior division of the obturator nerve, with variable branches from the common fibular nerve
Course	Forms a network around the popliteal vessels in the popliteal fossa and sends branches through the oblique popliteal ligament into the posterior knee
Sensory	Posterior knee joint capsule Posterior synovium and intra-articular structures of the knee

Clinical Relevance

Clinical Notes

The popliteal plexus is the main nerve supply of the posterior knee capsule and is a major source of posterior knee pain after total knee arthroplasty and in knee osteoarthritis. Local anaesthetic injected between the popliteal artery and the posterior capsule (the IPACK block) targets these branches, relieving posterior knee pain after knee replacement without weakening the leg. Posterior knee pain with fullness in the popliteal fossa should prompt assessment of the joint, the popliteal vessels (aneurysm, entrapment, cyst) and Baker cysts as well as the nerve supply.

Pathology

Common Injuries & Conditions

Posterior Knee Capsular Pain

Arthritis or capsular contracture sensitises the plexus, producing deep posterior knee pain on full flexion or extension; physiotherapy, posterior capsular injection or nerve-targeted procedures can help.

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