Gluteus medius muscle

The gluteus medius is a broad, thick, fan-shaped muscle forming the upper lateral part of the buttock. It is located deep to the gluteus maximus and superficial to the gluteus minimus.

Functionally, it is the chief abductor of the hip joint and a key stabilizer of the pelvis during locomotion — preventing the pelvis from dropping on the unsupported side during walking.

Origin

From the outer surface of the ilium between the iliac crest and the posterior gluteal line (above and posterior) and the anterior gluteal line (below). Also arises from the gluteal aponeurosis covering its outer surface.

Insertion

The fibres radiate downward and laterally from the ilium to the greater trochanter. They converge to form a strong, flattened tendon (tendon of gluteus medius muscle), which inserts onto the oblique ridge running downward and forward on the lateral surface of the greater trochanter of the femur.

Innervation

Superior gluteal nerve (L4, L5, S1) — emerges from above the piriformis muscle.

Function

Clinical correlates

• Superior gluteal nerve injury: Causes weakness or paralysis of gluteus medius and minimus → Trendelenburg sign positive (pelvic drop on contralateral side).

• Trochanteric bursitis: Inflammation of the bursa beneath its tendon produces tenderness and pain over the greater trochanter.

• Intramuscular injection landmark: The superolateral quadrant of the gluteal region overlies the upper gluteus medius — the safest injection site to avoid the sciatic nerve.