It is a broad and thick fleshy mass of a quadrilateral shape, and forms the prominence of the nates.
Its large size is one of the most characteristic features of the muscular system in humans, connected as it is with the power of maintaining the trunk in the erect posture. Other primates have much flatter buttocks.
The muscle is remarkably coarse in structure, being made up of fasciculi lying parallel with one another and collected together into large bundles separated by fibrous septa.
When the gluteus maximus takes its fixed point from the pelvis, it extends the femur and brings the bent thigh into a line with the body.
Taking its fixed point from below, it acts upon the pelvis, supporting it and the trunk upon the head of the femur; this is especially obvious in standing on one leg.
Its most powerful action is to cause the body to regain the erect position after stooping, by drawing the pelvis backward, being assisted in this action by the biceps femoris, semitendinosus, semimembranosus, and adductor magnus.
The gluteus maximus is a tensor of the fascia lata, and by its connection with the iliotibial band steadies the femur on the articular surfaces of the tibia during standing, when the extensor muscles are relaxed.
The lower part of the muscle also acts as an adductor and external rotator of the limb.
