Gluteus medius muscle
Gluteus medius is a large fan-shaped muscle located in the posterior hip, extending from the ilium to the proximal femur. Together with the gluteus maximus, gluteus minimus and tensor fasciae latae muscles, it belongs to the muscles of the gluteal region.
The gluteus medius muscle acts on the hip joint producing two movements; its anterior part internally rotates the thigh, while the contraction of the whole muscle abducts the thigh. Additionally, the gluteus medius muscle stabilizes the pelvis while standing or walking. This article will discuss the anatomy and function of the gluteus medius muscle.
|Origin||Gluteal surface of ilium (between anterior and posterior gluteal lines)|
|Insertion||Lateral aspect of greater trochanter of femur|
|Action||Hip joint: Thigh abduction, thigh internal rotation (anterior part); Pelvis stabilization|
|Innervation||Superior gluteal nerve (L4-S1)|
|Blood supply||Deep branch of superior gluteal artery, trochanteric anastomosis|
- Origin and insertion
- Blood supply
- Clinical relations
Origin and insertion
The gluteus medius muscle arises with a broad insertion from the gluteal surface of ilium. The area of attachment is large and it spans between the anterior and posterior gluteal lines. The muscle belly takes an anteroinferior course towards the proximal femur, gradually tapering in size and giving off a narrow tendon.
The tendon passes over the anterosuperior side of the greater trochanter, being separated from it by the trochanteric bursa of gluteus medius. Afterward, the muscle inserts to the lateral side of the greater trochanter of femur.
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Gluteus medius is a middle gluteal muscle, located deep to the gluteus maximus and superficial to the gluteus minimus. Only the posterior third of the muscle is covered by the gluteus maximus, whereas the larger anterior portion is covered by the deep fascia of the hip. This fascia is sometimes referred to as the gluteal aponeurosis. The posterior margin of the muscle lies anterior to the piriformis muscle, and sometimes it may be blended with it.
Gluteus medius is related to the branches of the superior gluteal artery and nerve, which run between the adjacent surfaces of the gluteus medius and minimus muscles. This is an important relation, as these vessels and nerves may be damaged during surgical procedures that involve the incision of gluteus medius.
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Gluteus medius is innervated by the superior gluteal nerve (L4-S1), which stems from the sacral plexus.
The blood supply to the gluteus medius muscle comes from the deep branch of superior gluteal artery. The tendon, however, is mainly supplied by the trochanteric anastomosis. This anastomosis is formed between the ascending branch of the medial circumflex femoral artery and descending branches of the superior gluteal and inferior gluteal arteries.
The gluteus medius muscle acts in synergy with gluteus minimus to perform these actions on the hip joint;
- When the proximal attachment of gluteus medius is fixed, the muscle can contract as a whole or it can contract with its anterior fibers only. In the former case, the axis of the movement goes through the hip joint and muscle pulls the greater trochanter superiorly and abducts the thigh. In the latter case, as the axis of the movement tilts anteriorly, the muscle causes the internal rotation of the thigh.
- When the distal attachment of the gluteus medius is fixed, the muscle pulls the ilium inferiorly, which results in the slight ipsilateral pelvic tilt and consequential raising of the pelvis on the opposite side. This action is important during walking, as it allows the raised leg from the opposite side to be moved towards the next step. Moreover, the strong tension generated within the muscle contributes to the stabilization of the pelvis and trunk during the gait cycle.
Peripheral injury of the superior gluteal nerve
A peripheral injury of the superior gluteal nerve may lead to loss of motor function. The classical sign is the pelvis dropping to the healthy side when standing on one leg (Trendelenburg’s sign). In order to maintain the balance, the patients compensatorily bend their upper body to the side of the stance leg. Furthermore, they walk with conspicuous sideward movements (Duchenne gait, also “waddling gait”).
When performing an intramuscular injection in the gluteal region, an injury of the sciatic nerve and superior gluteal nerve has to be avoided. Therefore, a recommended site of injection is the gluteus medius muscle in the upper outer quadrant of the buttock (Hochstetter's technique).