Gabriella Bargon, Sue Deacon, Sharon Tsang, Lena Wallin
Gluteus medius
The enveloping nature of the gluteus medius insertion clearly demonstrated that this muscle will have different functions depending on the position of the hip. In neutral, it is likely to have a strong abduction moment, since most of its fibers, particularly the middle part of the muscle belly, are parallel to the long axis of the femur. In stance (CKC), this enables the muscle to stabilise the pelvis on the femur. As the hip flexes, the anterior and middle fibers will form a right angle to the head of the femur and will function as internal rotators. As the hip extends, the same mechanism will occur with the posterior fibers and an external moment will be created. The posterior fibers of this muscle are frequently tested in a neutral hip position with abduction and external rotation (Kendall et al 1993, Sahrmann 2002). From the present anatomical study, the test appears to be appropriate. Similarly, the middle fibers should be tested in abduction between 0-40 degree of hip flexion and the anterior fibers in internal rotation at greater degrees of hip flexion.
