Gluteus maximus (Musculus glutaeus maximus) is the largest and most superficial of the three gluteal muscles, the muscles forming the buttock. It lies behind the pelvis and hip joint, beneath the skin and fatty tissue, and moves the thigh backwards while helping to support the trunk during demanding movements.
Where is gluteus maximus located?
Gluteus maximus occupies the posterior, or back, part of the hip region. It extends from the back of the pelvis towards the upper femur, the thigh bone, and the connective tissue along the outer thigh. Its bulk contributes substantially to the rounded contour of the buttock.
Its superficial surface, the surface nearest the skin, lies beneath subcutaneous tissue, the fatty connective tissue under the skin, and fascia, a sheet of connective tissue that surrounds muscles. Its deep surface faces the underlying muscles and bones. Gluteus maximus covers part of gluteus medius, a muscle on the outer pelvis that moves the thigh sideways and steadies the pelvis.
Deeper neighbours include piriformis and other short muscles that rotate the thigh outwards. The sciatic nerve, a major nerve passing towards the back of the thigh, runs deep to gluteus maximus. The ischial tuberosity, the bony prominence that supports body weight when sitting, also lies beneath its lower region when the hip is extended.
How are its fibres and surfaces arranged?
Gluteus maximus is a broad, thick muscle with fibres running mainly downwards and outwards from the pelvis. Fibres are the elongated muscle cells that shorten to generate force. Connective tissue partitions divide the muscle into conspicuous bundles.
The muscle has superficial and deep surfaces, an upper border and a lower border. Its upper and lower fibres have somewhat different directions of pull, so their contributions to movement are not identical. These regions are portions of one muscle rather than separate muscles.
Bursae lie between parts of its deep surface and underlying structures. A bursa is a small fluid-containing sac that reduces friction between moving tissues. One important bursa separates the muscle from the greater trochanter, the large bony projection on the outer side of the upper femur.
Where does gluteus maximus originate?
The origin is the muscle's attachment that is usually more stable during movement. Gluteus maximus has a broad origin from bone and connective tissue at the back of the pelvis:
- The posterior part of the iliac crest, the upper rim of the ilium, which is the broad upper part of the hip bone.
- The gluteal surface of ilium behind the posterior gluteal line, a bony ridge marking part of the muscle's attachment area.
- The posterior surface of the sacrum, the fused bone at the base of the spine.
- The posterior surface of the coccyx, the small terminal bone below the sacrum.
- The sacrotuberous ligament, a strong connective tissue band linking the sacrum and coccyx to the ischial tuberosity.
Additional fibres arise from nearby fascia, including the thoracolumbar fascia, the broad connective tissue sheet of the lower back. These attachments give the muscle an extensive base from which to pull on the thigh.
Where does gluteus maximus insert?
The insertion is the attachment that usually moves towards the origin when a muscle contracts. Gluteus maximus inserts into both a connective tissue tract and the femur. Most fibres join the iliotibial tract, a thickened band of fascia running down the outer thigh to the tibia, the larger lower-leg bone.
The deeper fibres of the lower portion attach to the gluteal tuberosity, a roughened area on the posterior upper femur. These attachments allow the muscle to act directly on the femur and to transmit tension along the outer thigh. Through the iliotibial tract, it also contributes to stability around the knee.
What movements does gluteus maximus produce?
Its main action is extension of the hip joint: moving the thigh backwards or straightening the hip from a bent position. It also produces lateral rotation, which turns the thigh outwards. When the thigh is fixed, the muscle can act on the pelvis and trunk instead.
| Action | Meaning | Contribution of gluteus maximus |
|---|---|---|
| Hip extension | Moving the thigh backwards or straightening a bent hip | A principal action of the muscle |
| Lateral rotation | Turning the thigh outwards | Pulls the femur into outward rotation |
| Hip abduction | Moving the thigh away from the body's midline | Assisted by the upper fibres |
| Hip adduction | Moving the thigh towards the body's midline | Assisted by the lower fibres |
Gluteus maximus is especially important when strong hip extension is required, such as rising from sitting, climbing stairs or running. It also helps control forward bending of the trunk at the hips. Its role therefore includes both producing movement and resisting movement under load.
What supplies its nerves and blood?
The inferior gluteal nerve supplies gluteus maximus. Its fibres arise from spinal nerve levels L5, S1 and S2: the fifth lumbar and first and second sacral levels. The nerve reaches the muscle on its deep surface.
Blood reaches the muscle through branches of the inferior and superior gluteal arteries. These vessels enter the gluteal region from the pelvis and distribute blood to the muscle and neighbouring tissues.
How can you orientate it in the 3D model?
In the 3D model next to the article, rotate to a posterior view, then select and isolate the left gluteus maximus or right gluteus maximus. Zoom and rotate to view the selected muscle from different angles. Fade or hide the selected muscle to change the view.