The gracilis is the most medial and superficial thigh muscle, a thin strap muscle spanning from the pubis to the medial tibia as part of the pes anserinus. It is the only adductor that crosses both the hip and knee joints, contributing to both adduction and knee flexion, though its contribution at each joint is modest. Its consistent anatomy and minimal functional sacrifice after harvest make it the most frequently used muscle in free flap reconstructive surgery.
| Origin | Body and inferior ramus of the pubis |
|---|---|
| Insertion | Upper medial surface of the tibia via the pes anserinus, alongside the sartorius and semitendinosus |
| Nerve Supply | Obturator nerve (L2, L3) |
| Blood Supply | Deep femoral artery via perforating branches |
| Actions | Adduction of the hip; Flexion of the knee; Internal rotation of the tibia when the knee is flexed |
|---|
Its dual-joint span allows it to simultaneously adduct the hip and flex the knee, coordination that is important during horse riding and ball trapping, though it is a minor contributor at both joints compared to the primary movers at each.
Gracilis tendinopathy at the pes anserinus insertion contributes to medial knee pain that is often confused with medial collateral ligament or meniscal pathology, producing pain at the medial tibia that worsens with resisted internal tibial rotation. The pes anserinus bursa between these tendons and the tibial collateral ligament is a source of medial knee pain in overweight or osteoarthritic individuals. Gracilis harvest for ACL reconstruction or free flap transfer leaves no clinically detectable functional deficit.
The gracilis tendon is the middle of the three pes anserinus tendons on the medial proximal tibia, palpable as a vertical cord during resisted knee flexion with internal tibial rotation.
Inflammation at the medial tibial insertion shared by gracilis, sartorius, and semitendinosus, producing medial knee pain distal to the joint line that worsens with stairs and squatting, common in overweight older adults and distance runners.
