Anatomy, Abdomen and Pelvis, Obturator Muscles

The word obturator comes from the Latin word obturo, which means “to stop or block up.” This adequately illustrates the location of the obturator muscles since they cover the opening of the obturator foramen. Both the obturator externus and obturator internus are bilateral-triangular shaped muscles. Generally, they originate from the obturator membrane and pelvic bone and attach to the greater trochanter of the femur. They are both considered a part of the muscle group that externally rotates the hip along with gemellus superior and inferior, piriformis, and quadratus femoris. See Pelvic Region Anatomy. The main functions of the obturator internus are to externally rotate the femur when the hip is extended and abduct the femur when the hip is flexed. Additionally, the obturator internus plays a vital role in stabilizing the femoral head in the acetabulum. As a result, this muscle can be injured or weakened by posterior dislocations of the hip since the bone is driven back into the obturator internus and gluteal muscles. Similar to the obturator internus, the primary function of the obturator externus is to externally rotate the hip. It can assist with this movement when the hip is in either the neutral or flexed position. It has also been shown that this muscle can assist with the adduction of the flexed hip. Due to their function and location, they both can be damaged in sporting activities involving kicking, tackling, and falling. Sprains to these muscles are rare, but when they do occur, young male athletes are most often affected.