Gluteus maximus extends; gluteus medius/minimus abduct and stabilise the pelvis
Mnemonic
“Gluteus medius, gluteus minimus and tensor fasciae latae”, all supplied by the superior gluteal nerve (L4, L5, S1).
The rule to remember is that the superior gluteal nerve abducts, while the inferior gluteal nerve extends through gluteus maximus.
Loss of the superior gluteal nerve gives a positive Trendelenburg sign: the pelvis drops on the unsupported side when standing on the affected leg, because the abductors on the standing side cannot hold it level. The patient compensates by lurching the trunk over the affected hip, giving the Trendelenburg gait.
Learning note
Gluteus maximus is the major hip extensor. Gluteus medius and minimus are important hip abductors and pelvic stabilisers during walking.