Gluteus maximus muscle

The gluteus maximus is the main extensor muscle of the hip.

It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips.

Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks.

The other gluteal muscles are the medius and minimus, and sometimes informally these are collectively referred to as the "glutes".

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 hips and can not sustain standing erectly.

The muscle is made up of muscle fascicles lying parallel with one another, and collected together into larger bundles separated by fibrous septa.