The Gluteus Maximus
Among the three muscles, the gluteus maximus is the most superficial muscle. Its thick muscle fibre carefully protects and hides away the sciatic nerve. The gluteus maximus extends the hip joint during running and walking uphill, but does not act in relaxed walking. The upper fibres of the gluteus maximus muscles permit transverse hip abduction, hip rotation and external hip rotation movements. The lower muscle fibres on the other hand allow the same movement with the addition of hip adduction.
The Gluteus Medius
The intermediately placed, more lateral gluteus medius is a major abductor of the hip joint and an important stabilizer of the pelvis when the opposite lower limb is lifted off the ground. Because of its stabilizer function, it prevents the pelvis from tilting towards the side with no support.
The muscle acts as a level control for the hips, which originates at the iliac crest and continues all the way as it attaches to the femur. When the gluteus medius is injured, it affects our walking gait and medical professionals refer to this as a positive trendelenburg sign.
The Gluteus Minimus
The deepest layer of gluteal muscles is the gluteal minimus and the lateral rotators of the hip joint. They fill up the greater and lesser sciatic notches. These muscles generally insert at the posterior aspect of the greater trochanter of the femur. The gluteal muscles correspond to some degree with the rotator cuff of the shoulder joint: lateral rotators posteriorly, abductor superiorly, medial rotators anteriorly.
When compared to the other two muscles in the gluteal region, the gluteus minimus is the smallest. Thanks to this muscle, we are able to perform our daily activities smoothly. The gluteus minimus is responsible for abduction of your thigh, which means it moves the thigh away from your body. Now try getting out of your car without the gluteus minimus working.
The iliotibial tract runs from the ilium towards the tibia. It helps to stabilize the knee joint laterally. It is characterized by the thickening of the deep fascia of the thigh. The muscle tensor fasciae latae, a frequently visible and palpable flexor and medial rotator of the hip joint, inserts into this fibrous band, tensing it. Despite its major flexor function, this anterolaterally-placed muscle is considered a part of the more posterior gluteal group. It shares its insertioin into the iliotibial tract with gluteus maximus and it is supplied by the superior gluteal nerve and artery.
The muscles in the gluteal region are considered to be one of the strongest muscles in the body. Moreover, the adipose concentration in the buttocks is unique among humans, being the only living being with such characteristic. This complex structure that we use every day is prone to injury. An understanding on the underlying actions and functions of these muscles will aid us in better understanding the roles it plays.