The Gluteus Maximus Muscle
The gluteus maximus muscle is the largest of three gluteal muscles (other two are gluteus medius muscle and gluteus minimus muscle). By laying over the gluteus medius and minius muscles, it builds the most superficial layer of the dorsal gluteal musculature and thus forms the surface anatomy of the gluteal region.
It is the main extensor muscle of the hip, which significantly contributes maintaining the trunk in the erect posture. For this reason, primates that can not sustain standing erectly, have much flatter hips.
Lateroposterior surface of sacrum and coccyx
Gluteal tuberosity of femur
|Innervation||Inferior gluteal nerve (L5, S1, S2)|
Thigh adduction (inferior part)
This article will discuss the anatomy and significance of the gluteus maximus muscle.
Anatomy and supply
Its inferiormost fibers insert at the gluteal tuberosity of the femur. On the contrary, the more superior fibers go over into the iliotibial tract, a strong fibrous band at the outside of the thigh inserting at the lateral condyle at the tibia. The gluteal fold (or crease) does not represent the lower margin of the muscle but rather results from an arcuate enhancement of the fascia.
The innervation is supplied by the inferior gluteal nerve, a branch of the sacral plexus (L5-S2). Numerous vessels and nerves run under the gluteus maximus muscle, including the sciatic nerve, the pudendal nerve and the superior gluteal vessels.
The gluteus maximus muscle is the most powerful extensor and external rotator of the hip. Furthermore it supports the stabilization of the hip joint. The contraction of the superior part of the muscle leads to abduction whereas the contraction of the inferior part causes an adduction. The iliotibial tract enhances the lateral thigh fascia and thus relieves the pressure of the femur (tension band principle).
Lesions of the inferior gluteal nerve (e.g. through traumas, hernias or pelvic tumors) may lead to functional deficiency of the gluteus maximus muscle.
The affected patients have tremendous difficulties walking up the stairs or standing up from the chair. The standing position itself however is commonly without pathological findings as it is usually compensated by the ischiocrural musculature.
Purulent inflammations underneath the gluteus maximus muscle often remain unnoticed and may spread into neighboring structures (sinking abscess). Because of that and the high risk of nerve or vessel injury an intramuscular injection is not to be administered into the gluteus maximus muscle. The choice of injection site should be preferably the gluteus medius muscle.