The muscle indicated is the obturator externus muscle.

The obturator externus is one of six muscles in the medial compartment of the thigh. The thigh consists of three muscular compartments:

1. Anterior
2. Medial
3. Posterior

The medial compartments consists of the following muscles:

• Gracilis
• Pectineus
• Adductor longus
• Adductor brevis
• Adductor magnus
• Obturator externus

All the muscles of the medial compartment are innervated by the obturator nerve except for the pectineus (femoral nerve) and the hamstring part of the adductor magnus (tibial division of sciatic). The muscles of the medial compartment generally serve to adduct the thigh at the hip joint.

There are two obturator muscles: obturator externus and obturator internus. The obturator muscles are attached to the obturator membrane which covers the obturator foramen of the pelvic bone. The obturator externus as the name suggests is located on the external surface of the obturator membrane and belongs to the medial compartment of thigh muscles. The obturator internus is located internally on the pelvis and belongs to the deep group of gluteal muscles.

Origin: obturator membrane, anterior obturator foramen

Insertion: posteriomedial surface of greater trochanter of femur in lateral wall of trochanteric fossa

Action: obturator nerve

Innervation: lateral rotation of hip. Assists hip adduction.

Learn more about the anatomy of the thigh muscles in this anatomy tutorial.