Gluteus maximus is the largest muscle by volume. Its dual insertion — 25% into the gluteal tuberosity and 75% into the ITB — means it primarily acts on the knee through the ITB rather than directly at the hip.
| Origin | Posterior ilium behind posterior gluteal line, sacrum and coccyx lateral surfaces, sacrotuberous ligament |
|---|---|
| Insertion | Gluteal tuberosity of femur (deep, 25%) and iliotibial band (superficial, 75%) |
| Nerve Supply | Inferior gluteal nerve (L5, S1, S2) |
| Blood Supply | Inferior gluteal artery |
| Actions | Hip extension — most powerful extensor; External hip rotation; Lower fibres assist hip abduction via ITB; Powers hip extension thrust in running and climbing |
|---|
Gluteus maximus weakness produces Trendelenburg gait. It is the donor for SGAP and IGAP perforator flaps for breast reconstruction. In posterior hip arthroplasty, the splitting approach requires careful posterior capsule repair for stability.
The dominant posterior buttock muscle — palpated during resisted hip extension in prone.
Posterior hip arthroplasty through the gluteus maximus split requiring posterior capsule and external rotator repair to minimise dislocation risk.
