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Gluteus Muscle – Origin, Nerve Supply, Function

The gluteal muscles are a group of three muscles that make up the buttocks: the gluteus maximus, gluteus medius, and gluteus minimus. The three muscles originate from the ilium and sacrum and insert on the femur. The functions of the muscles include extension, abduction, external rotation, and internal rotation of the hip joint.

Gluteus muscle, any of the large, fleshy muscles of the buttocks, stretching from the back portion of the pelvic girdle (hipbone) down to the greater trochanter, the bony protuberance at the top of the femur (thighbone). These include the gluteus maximus, gluteus medius, and gluteus minimus.

The gluteus maximus is the most superficial as well as the largest of the three muscles and makes up most of the shape and form of the buttock and hip area. The gluteus maximus is a thick fleshy muscle with a quadrangular shape. It is a large muscle and plays a prominent role in the maintenance of keeping the upper body erect.

The gluteal muscles are a grouping of muscles that make up the buttock area. These muscles include

Gluteus maximus
Gluteus medius
Gluteus minimus

The gluteus maximus attaches to many bony compartments including

The inner upper ilium
Ilium crest
The lower part of the sacrum
Coccyx

The gluteus maximus has two insertion points – superficial fibers to the greater trochanter and a band of the fascia lata and the deep fibers that insert into the gluteal tuberosity between the adductor magus and vastus lateralis. It originates in the gluteal surface of the ilium.[rx] The gluteus maximus also has associations with three bursae.[rx][rx][rx] These include:

The trochanteric bursa – separates the gluteus maximus from the greater trochanter
Ischial bursa – separates the gluteus maximus from the ischial tuberosity
The gluteofemoral bursa – separates the iliotibial tract from the vastus lateralis

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Gluteus Maximus

The gluteus maximus is the largest of the gluteal muscles. It is also the most superficial, producing the shape of the buttocks.

Attachments: Originates from the gluteal (posterior) surface of the ilium, sacrum and coccyx. It slopes across the buttock at a 45 degree angle, then inserts into the iliotibial tract and the gluteal tuberosity of the femur.
Actions: It is the main extensor of the thigh, and assists with lateral rotation. However, it is only used when force is required, such as running or climbing.
Innervation: Inferior gluteal nerve.

Gluteus Medius

The gluteus medius muscle is fan-shaped and lies between to the gluteus maximus and the minimus. It is similar in shape and function to the gluteus minimus.

Attachments: Originates from the gluteal surface of the ilium and inserts into the lateral surface of the greater trochanter.
Actions: Abducts and medially rotates the lower limb. During locomotion, it secures the pelvis, preventing pelvic drop of the opposite limb. (Note: the posterior fibres of the gluteus medius are also thought to produce a small amount of lateral rotation).
Innervation: Superior gluteal nerve.

Gluteus Minimus

The gluteus minimus is the deepest and smallest of the superficial gluteal muscles. It is similar is shape and function to the gluteus medius.

Attachments: Originates from the ilium and converges to form a tendon, inserting to the anterior side of the greater trochanter.
Actions: Abducts and medially rotates the lower limb. During locomotion, it secures the pelvis, preventing pelvic drop of the opposite limb.
Innervation: Superior gluteal nerve.

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Nerves

The innervation of the gluteus maximus muscle is from the inferior gluteal nerve. The inferior gluteal nerve originates from the ventral rami of L5, S1, and S2. Classically, the inferior gluteal nerve was thought not to provide cutaneous innervation. However, the recent literature describes findings of cutaneous branches of the nerve which might contribute toward gluteal pain during lumbar disk herniation. Surgeons must also be aware of this nerve as an injury might result in compression ulcers and various pain syndromes.[rx][rx]

Muscles

The gluteus maximus works with the semitendinosus and semimembranosus muscles to extend the hip. The muscle also works in conjunction with the iliopsoas, piriformis, and the obturator muscles to externally rotate the hip.

Structure and Function

The principal function of the gluteus maximus is to extend and externally rotate the thigh. Although a powerful extensor, it only acts when force is necessary. These situations include rising from sitting, straightening from a bending position, walking up stairs or on a hill, and running. It also acts on the pelvis, supports it, and the trunk which is vital when a person is standing on one leg. By attaching to the tensor fascia lata, the gluteus maximus also steadies the femur.[rx][rx]

The functions of muscles include extension, abduction, lateral(external) rotation, and medial (internal) rotation of the hip joint. The gluteus maximus also supports the extended knee through the iliotibial tract.

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