Gluteus Maximus
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Direct answer
Gluteus maximus is the largest, coarsest and most superficial muscle of the gluteal region, forming the contour of the buttock. It takes origin from the back of the ilium behind the posterior gluteal line, the dorsal surfaces of the sacrum and coccyx, and the sacrotuberous ligament, and is inserted into the iliotibial tract and the gluteal tuberosity of the femur. Supplied by the inferior gluteal nerve (L5, S1, S2), it is the powerful extensor of the hip from the flexed position.
What you must remember
- Origin: gluteal surface of the ilium behind the posterior gluteal line, dorsal aspect of the sacrum and coccyx, sacrotuberous ligament, and the fascia over gluteus medius (aponeurotic part).
- Insertion: roughly three-quarters of the muscle into the iliotibial tract, and one-quarter into the gluteal tuberosity of the femur.
- Nerve supply: inferior gluteal nerve (L5, S1, S2), which enters its deep surface below piriformis; the muscle also receives its blood supply from the inferior gluteal artery with contributions from the superior gluteal artery.
- Actions: extension and lateral rotation of the hip from the flexed position — as in rising from sitting, climbing stairs, running and jumping; it tense the fascia lata through the iliotibial tract and helps support the extended knee; it is little used in easy walking.
- Structures deep to the muscle: the short lateral rotators, the sciatic nerve, the pudendal nerve and internal pudendal vessels, and the posterior cutaneous nerve of the thigh — all at risk from injections placed too low and medially.
- Bursae: a large trochanteric bursa over the greater trochanter, an ischial bursa over the ischial tuberosity, and a bursa between the muscle and the vastus lateralis attachment — sites of bursitis.
- Clinical importance: pressure sores over the ischial tuberosity and sacrum; inferior gluteal nerve palsy weakens extension, making stair-climbing and rising from a chair difficult, with a characteristic backward-leaning gluteal gait; hamstring origin avulsion injuries near its attachment area.
Common confusion
Students swap the nerve supplies of the two gluteal muscles: gluteus maximus is supplied by the inferior gluteal nerve, while medius and minimus are supplied by the superior gluteal nerve. Also, gluteus maximus is a hip extensor used for powerful activities, not the main muscle of level walking — the hamstrings and passive mechanics cover easy gait. Its insertion must not be quoted as the greater trochanter; it descends well below it into the iliotibial tract and gluteal tuberosity.
Exam-focused takeaway
Theory questions ask for origin, insertion, nerve supply and actions with a note on why it is described as a muscle of climbing and running. Practical and viva examiners test its lower border in relation to the sciatic nerve, the safe gluteal injection site, and the difference between gluteal gait (extension weakness) and Trendelenburg gait (abductor weakness).
Frequently asked questions
What is the nerve supply of gluteus maximus?
The inferior gluteal nerve (L5, S1, S2), which reaches its deep surface after leaving the pelvis below piriformis. The blood supply is chiefly from the inferior gluteal artery.
Where exactly is gluteus maximus inserted?
Chiefly into the iliotibial tract, which transmits its pull to the lateral condyle of the tibia, and partly into the gluteal tuberosity of the femur. This dual insertion lets it extend both the hip and, indirectly, support the knee.
What are its chief actions?
Powerful extension and lateral rotation of the hip from the flexed position, and steadying the thigh on the leg in standing. Through the iliotibial tract it also supports the extended knee.
Which structures lie deep to gluteus maximus?
The sciatic nerve, posterior cutaneous nerve of the thigh, pudendal nerve and internal pudendal vessels, the inferior gluteal vessels, and the short lateral rotators of the hip. This relations list explains why injections must avoid the lower medial quadrant.
What happens in inferior gluteal nerve palsy?
Gluteus maximus is paralysed, so the patient cannot extend the hip forcefully — rising from a chair, climbing stairs and running are difficult. The patient leans backwards on walking (gluteal gait), and the buttock shows wasting.