The structure indicated is the gluteus minimus.
The gluteus minimus muscle is one of the muscles of the gluteal region. The muscles in the gluteal region are divided into a superficial and deep group. There are four muscles of the superficial group:
- Gluteus maximus
- Gluteus medius
- Gluteus minimus
- Tensor fasciae latae
There are 5 muscles in the deep group:
- Gemellus superior
- Gemellus inferior
- Quadratus femoris
- Obturator internus
Origin: Dorsal ilium between inferior and anterior gluteal lines and edge of greater sciatic notch.
Insertion: lateral and superior surfaces of greater trochanter
Action: Hip abduction, hip medial rotation (anterior fibres), hip lateral rotation (posterior fibres)
Innervation: Superior gluteal nerve
Learn more about the anatomy of the gluteal muscles in this tutorial.