Gluteus maximus is the largest muscle in the body and forms the bulk of the buttock on each side. It arises from several contiguous sites:

• external surface of ilium posterior to the posterior gluteal line
• posterior third of iliac crest
• lumbar fascia
• lateral mass of the sacrum
• sacrotuberous ligament

Passing inferolaterally, it inserts into two contiguous structures:

• the majority of fibres insert into the iliotibial tract; this passes inferiorly to insert into the anterior surface of the lateral tibial condyle
• a minority of fibres insert into the gluteal tuberosity on the posterior, superior third of the femur

Gluteus maximus is innervated by the inferior gluteal nerve (L5-S2).

Its actions are varied:

• main extensor of the thigh at the hip
• lateral rotation of thigh at the hip
• facilitates knee extension via the iliotibial tract

It is associated with a number of bursae.