Gluteus medius muscle

At a glance

English

Gluteus medius muscle

Latin (TA2)

Musculus gluteus medius

System

Muscle

Region

Lower limb

Side

Paired, left and right

About the gluteus medius muscle

Gluteus medius is the middle of the three gluteal muscles in both size and depth. It is a thick, radiating sheet covering much of the ilium's outer face, between gluteus maximus behind and gluteus minimus beneath it. Only its back third is covered by gluteus maximus; the front two-thirds lie under a strong layer of deep fascia, the gluteal aponeurosis, and can be felt just below the iliac crest.

Its fibres come from the wide band of the ilium's outer face that lies between the anterior and posterior gluteal lines, below the iliac crest, and from the aponeurosis covering it. Its fibres converge, the front ones running down and back and the back ones down and forwards, onto a strong flat tendon. This fixes to a ridge that slants downwards and forwards across the trochanter's outer face. A bursa between the tendon and the trochanter lets it glide; its back edge is sometimes joined to piriformis.

Acting as a whole, the muscle abducts the thigh, but its key job is the reverse action: with the foot planted, it pulls on the pelvis to stop the opposite side from dropping when the other leg is lifted, as happens with every step. Its front fibres also help flex and medially rotate the hip, and its back fibres help extend and laterally rotate it. In walking, the back fibres slow inward rotation of the thigh at the end of the swing phase.

Weakness of gluteus medius, or injury to its nerve, the superior gluteal nerve, shows as a positive Trendelenburg sign: standing on the affected leg, the pelvis sags on the other side. In walking, people lurch the trunk over the weak side to compensate. The nerve can be harmed by a badly placed buttock injection or hip surgery. Pain over the trochanter from a tendinopathy of this muscle and minimus, or from the bursa, is a common cause of outer hip pain, especially in middle age.

Attachments, action and supply

Origin

Outer face of the ilium, between its anterior and posterior gluteal lines, below the iliac crest, and the gluteal aponeurosis.

Insertion

Oblique ridge across the outer face of the femur's greater trochanter.

Action

Abducts the thigh and keeps the pelvis level during single-leg stance; front fibres flex and medially rotate, back fibres extend and laterally rotate the hip.

Nerve supply

Superior gluteal nerve (L4, L5, S1).

Blood supply

Superior gluteal artery, mainly its deep branch, with a contribution from the trochanteric anastomosis.