The deep layers of the gluteal muscles are also commonly referred to as “the rotators”. They are a dense strip of 5 muscles and are responsible for laterally rotating the thigh and helping to stabilize the femoral head in the acetabulum.
The piriformis is considered to be a landmark of the gluteal region and renowned because it is covers the sciatic nerve and can play a role in the developing and relieving of sciatic nerve pain. The piriformis originates on the anterior sacrum and attaches to the greater trochanter of the femur.
The obteratur internus and superior and inferior gemelli combine to form a three headed muscle and are sandwiched between the piriformus and the quadratus femoris. They share a common horizontal tendon, which runs from the superior ischial tuberosity to the greater trochanter.
All four muscles (pirifomus, obteratur internus and the gemelli) work together to rotate an extend thigh and abduct the flexed thigh and hug the head of the femur into the joint.
The short thick quadratus femoris sits at the bottom of this group of muscles and originates on the lateral ischial tuberosity and attaches to the top of the femur and is also a strong lateral rotator of the thigh.