Inferior Gemellus

General information

Inferior gemellus is a hip joint muscle in the deep hip rotator group.

Literal meaning

The lower little twin muscle.

Interesting information

Inferior gemellus is situated in the pelvic region between obturator externus and obturator internus. Its primary function is to laterally rotate and stabilize the hip joint. There are a total of six hip rotator muscles: piriformis, obturator externus/internus, quadratis femoris, and gamellus inferior/superior.

Functionality of inferior gemellus can be assessed by having a patient sit with their hips forming a ninety-degree angle. The patient must then externally rotate the hip. Any limitation in the range of movement or pain may indicate injury or dysfunction in inferior gemellus.

Injury to inferior gemellus may make daily leisure activities difficult to perform. For instance, any activities which require maneuvering while in a squatting position like gardening will cause pain and discomfort.

Asymmetrical training of inferior gemellus will result in discomfort, decreased range of movement on the weaker side, and loss of hip rotation function. Care should be taken to complete strengthening exercises and stretches equally on both sides. If one side appears to be weaker you should complete additional sets on that side.

Origin

Tuberosity of the ischium and the lateral obturator ring.

Insertion

Greater trochanter of the femur (medially).

Function

Laterally rotates the hip joint and assists in abduction of a flexed thigh.

Nerve supply

Nerve to quadratis femoris.

Blood supply

Inferior gluteal artery.

Relevant research

Retrotrochanteric gluteal and thigh pain (sciatica-like pain) may be indicative of injury to the gemelli-obturator internus complex. This has important implications for the diagnosis and treatment of debilitating gluteal pain.

Cox JM, Bakkum BW. (2005). “Possible generators of retrotrochanteric gluteal and thigh pain: the gemelli-obturator internus complex”. J Manipulative Physiol Ther. 28(7):534-8.

Recent literature usually classifies gemellus inferior, gemellus superior, and obturator internus as discrete muscles. Muscle categorization has traditionally been highly dependent on nerve supply. However, if nerve supply alone is used to classify these three muscles then they should be considered different heads of a single muscle rather than completely separate muscles.

Shinohara, Harumichi (1995). “Gemelli and obturator internus muscles: Different heads of one muscle?” The Anatomical Record 243, S. 145-150.

Inferior gemellus exercises

One of the best exercises to perform to strengthen the hip rotators, including inferior gemellus, is a three point hip rotation. Position yourself on your hands and knees on a flat but comfortable surface. Bring your right knee in to your chest with your knee flexed (bent). Then rotate your leg out to the right and then to the back. Bring the knee back to your chest. Complete a total of ten rotations on each leg. Make sure your movement is smooth and controlled throughout the exercise. This exercise can also be completed in a standing position.