The articularis genu is a small muscle slip deep to the vastus intermedius that attaches to the knee joint capsule and the suprapatellar pouch. Its sole function is to pull the suprapatellar pouch superiorly during knee extension, preventing the synovial tissue from being pinched between the femur and patella during full extension. Its failure after knee surgery or from adhesions produces suprapatellar pouch impingement contributing to post-operative knee stiffness.
| Origin | Anterior surface of the distal femur — a small muscle slip from the distal vastus intermedius |
|---|---|
| Insertion | Superior margin of the knee joint capsule and suprapatellar pouch |
| Nerve Supply | Femoral nerve (L2, L3, L4) |
| Blood Supply | Lateral circumflex femoral artery |
| Actions | Retracts the suprapatellar pouch during knee extension preventing its impingement between the femur and the patella |
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Without the articularis genu actively retracting the suprapatellar pouch during knee extension, the synovial tissue would fold into the joint and be progressively nipped, producing inflammation, pain, and eventual suprapatellar fibrosis restricting extension.
Arthrofibrosis of the knee — pathological scarring of the joint that severely restricts range of motion — involves the suprapatellar pouch and can obliterate it completely. The articularis genu's failure to retract an already scarred pouch perpetuates the stiffness. Manipulation under anaesthesia and arthroscopic lysis of adhesions target the suprapatellar pouch as a primary site of arthrofibrosis.
The articularis genu is not individually palpable — it lies deep to the vastus intermedius and is only identifiable on surgical dissection or MRI.
Post-surgical suprapatellar fibrosis from articularis genu failure to retract the inflamed pouch producing progressive knee extension loss, managed with manipulation under anaesthesia and arthroscopic adhesiolysis.
