Muscles abducting the hip joint

Gluteus maximus

Gluteus medius

Gluteus minimus

Tensor fascia latae

Gluteus medius

Gluteus medius is situated on the lateral and upper part of the buttock, just below the iliac crest. It must be considered to be a close companion of gluteus maximus and is in fact overlapped by this muscle from the back. It is fan-shaped, having its broad part above and its tendon below. It fills the space between the iliac crest and the greater trochanter of the femur.

Its upper attachment is to the gluteal, or lateral surface of the ilium between the posterior and anterior gluteal lines. This area is quite extensive reaching to the iliac crest above and almost as far as the sciatic notch below. The muscle is covered with a strong layer of fascia from the deep surface to which it has a firm attachment. It shares the posterior part of this fascia with gluteus maximus.

The posterior fibres pass downwards and forwards, the middle fibres pass straight downwards and the anterior fibres pass downwards and backwards. The fibres come together and form a flattened tendon which attaches to a roughened area, which runs downwards and forwards, visible on the superolateral side of the greater trochanter of the femur. The tendon is separated from the trochanter by a bursa, whose position is given by a smooth area on the trochanter in front of the attachment of the tendon.

Nerve supply

Gluteus medius is supplied by the superior gluteal nerve, root value L4, 5, S1. The skin covering the muscle is mainly supplied from L1, 2.

Action

With the pelvis fixed, gluteus medius will pull the greater trochanter of the femur upwards. However, as the fulcrum of the movement is at the hip joint, this will cause the femoral shaft to move laterally, this is termed abduction.

If the lower attachment of the muscle is fixed it will pull down the wing of the ilium, producing a downward tilting of the pelvis to the same side and, of course, a raising of the pelvis on the opposite side. In additioin, the anterior fibres of gluteus medius acting from a fixed pelvis will help with medial rotation of the femur. Acting with the femur  fixed, these fibres rotate the opposite side of the pelvis forward.

Functional activity

Gluteus medius plays a vital role in walking, running and when bearing weight on one limb. When the opposite limb is taken off the ground the pelvis on that side would tend to drop through loss of support from below. Gluteus medius on the supporting side works very hard to maintain, or even raise a little, the opposite side of the pelvis, allowing the raised limb to be brought forward for the next step. If the muscle is paralysed the pelvis drops on the opposite side during this manoeuvre.

In walking or running, not only is gluteus medius important for support, but with the help of other muscles, such as gluteus minimus and tensor fascia lata, it produces a rotation of the hip joint. This time with the femur the more fixed point, it controls the pelvic rotation on the same side.

If the muscle is unable to work efficiently due to paralysis or poor mechanics of the hip joint, the pelvis will drop on the opposite side. This is reffered to as a Trendelburg sign. Walking in the case is awkward and difficult, and running virtually impossible.

Palpation

Find the middle of the iliac crest, which is directly above the greater trochanter of the femur. About two fingers’ breadth below this region is the bulk of the muscle. Now stand alternately on one limb and then the other; you will feel the muscle become hard as the weight is borne on the same limb. Place the fingers of the other hand on the opposite side; walk slowly down the room. You will feel the two muscles coming into action alternately.

A patient with a Trendelburg gait, either on one or both sides, compensates for the lack of support of the swing limb by throwing the trunk over the supporting limb so that the weight is balanced over the hip, thus giving time to swing the limb through.

Gluteus minimus

Although this is the smallest of the gluteal muscles it takes the largest attachment from the gluteal surface of the ilium. It is triangular in shape, being wide at the top and narrowing to a tendon below.

Its upper attachment is from the gluteal surface of the ilium in front of the anterior and above the inferior gluteal lines, reaching as far forward as the anterior border of the ilium in front and almost to the sciatic notch behind. Its fibres pass downwards, backwards and slightly laterally forming a tendon which attaches to a small depression on the anterosuperior aspect of the greater trochanter of the femur.

Nerve supply

Gluteus minimus is supplied by the superior gluteal nerve, root value L4, 5, S1. The skin overlying the muscle is mainly supplied by L1.

Action

If the upper attachment of the muscle is fixed, contraction of its anterior fibres will medially rotate the femur. This is because the femoral attachment lies lateral to the fulcrum of the movement, the hip joint. If the lower attachment is fixed, the muscle will raise the opposite side of the pelvis in a similar way to gluteus medius. It will also, by pulling the front of the ilium outwards, swing the opposite side of the pelvis forwards.

Functional activity

This muscle appears to play its most important role in the support and control of pelvic movements. It is a well-developed and powerful muscle, using its power to a maximum in walking and running when the opposite limb is off the ground. As the limb is swung forward, the pelvis on the same side is also swung forward. This uses the hip of the weight-bearing limb as the fulcrum of the movement, with gluteus medius and minimus both supporting the pelvis and swinging it forward on the opposite side.

Palpation

Find the anterior superior iliac spine at the front of the iliac crest. Allow the pads of your finger to slip downwards and backwards towards the greater trochanter of the femur. Within two fingers’ breadth you will be on the muscle bulk. Now rotate the lower limb medially and you will feel the muscle belly contracting hard. Do the same on the opposite side of the body and then begin to walk forward. You will feel the muscles contracting alternately, as each limb becomes weight-bearing.

Tensor fascia latae

Tensor fascia latae is situated anterolateral to the hip joint and superficial to gluteus minimus. It attaches above to the anterior part of the outer lip of the iliac crest, between and including the iliac tubercle and the anterior superior iliac spine, the area of gluteal surface just below it, the fascia between it and gluteus minimus and that covering its superficial surface. Inferiorly, it attaches between the two layers of the iliotibial tract, below the level of the greater trochanter. 

Nerve supply

Tensor fascia latae is supplied by the superior gluteal nerve, root value L4, 5, with the skin overlying the muscle supplied by L1.

Action

This muscle overlies gluteus minimus and helps in flexion, abduction and medial rotation of the hip joint. It also straightens out the backward pull of gluteus maximus on the iliotibial tract.

Acting with the superficial fibres of gluteus maximus it will tighten the iliotibial tract, and through its attachment to the lateral condyle of the tibia, will extend the knee joint. Acting with gluteus minimus it will medially rotate the hip joint and its posterior fibres may help in abduction of the thigh.

Functional activity

Due to the fact that this muscle, together with gluteus maximus, links the pelvis with the tibia it will help to steady and control the movements of the pelvis and femur on the tibia when the limb is weight-bearing. Tensor fascia latae produces strong medial rotation when the hip is in extension and the lower limb, pelvis and trunk are prepared to take the thrust relayed through the lower limb by the calf muscles during the “toe-off” phase of walking.

When the quadriceps femoris is paralysed, tensor fascia lata can be developed to produce sufficient extension of the knee to enable the patient to walk, but its action is only weak and limited in range.

Palpation

Place the fingers half way between the anterior superior iliac spine and the greater trochanter of the femur. When the lower limb is medially rotated, the muscle can be felt to contract powerfully. If the weight is taken on the limb and the pelvis is rotated to the same side, a similar contraction of the muscle will be observed.