The gemelli muscles are the inferior gemellus muscle and the superior gemellus muscle, two small accessory fasciculi to the tendon of the

internal obturator muscle The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis. It exits the pelvic cavity through the lesser sciatic foramen. The ...

. The gemelli muscles belong to the

lateral rotator group The lateral rotator group is a group of six small muscles of the hip which all externally (laterally) rotate the femur in the hip joint. It consists of the following muscles: piriformis, gemellus superior, obturator internus, gemellus inferio ...

of six muscles of the hip that rotate the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

in the hip joint.

Superior gemellus muscle

The gemelli muscles are two small muscular

fasciculi Fascicle or ''fasciculus'' may refer to: Anatomy and histology * Muscle fascicle, a bundle of skeletal muscle fibers * Nerve fascicle, a bundle of axons (nerve fibers) ** Superior longitudinal fasciculus *** Arcuate fasciculus ** Gracile fas ...

, accessories to the tendon of the

which is received into a groove between them. The superior gemellus muscle is the higher placed gemellus muscle that arises from the outer (gluteal) surface of the

ischial spine The ischial spine is part of the posterior border of the body of the ischium bone of the pelvis. It is a thin and pointed triangular eminence, more or less elongated in different subjects. Structure The pudendal nerve travels close to the ischia ...

, and blends with the upper part of the tendon of the internal obturator. It is smaller than the inferior gemellus. In some people, the fibres of the gemellus superior extend further than average, and are prolonged onto the medial surface of the

greater trochanter The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Stan ...

of the femur. The superior and inferior gemelli are supplied by the

inferior gluteal artery The inferior gluteal artery (sciatic artery), the smaller of the two terminal branches of the anterior trunk of the internal iliac artery, is distributed chiefly to the buttock and back of the thigh. It passes down on the sacral plexus of nerves ...

. Nerve supply to the superior gemellus is from the supply to the internal obturator – L5, S1, and S2.

Inferior gemellus muscle

The inferior gemellus muscle arises from the upper part of the

ischial tuberosity The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large swelling posteriorly on the superior ramus of the ischium. It marks th ...

, immediately below the groove for the internal obturator tendon. It blends with the lower part of the tendon, and is inserted with it into the medial surface of the

. It is rarely absent. Like the internal obturator muscle, the gemellus superior and gemellus inferior help to steady the femoral head in the acetabulum. Both muscles also help to laterally rotate the extended thigh and abduct the flexed thigh at the hip by assisting the internal obturator. The gemelli muscles act to compensate the reduced power of the internal obturator as it turns around the

lesser sciatic notch Below the ischial spine is a small notch, the lesser sciatic notch; it is smooth, coated in the recent state with cartilage, the surface of which presents two or three ridges corresponding to the subdivisions of the tendon of the Obturator internu ...

. Blood supply is from the inferior gluteal artery. Nerve supply is from the supply to the

quadratus femoris The quadratus femoris is a flat, quadrilateral skeletal muscle. Located on the posterior side of the hip joint, it is a strong external rotator and adductor of the thigh, but also acts to stabilize the femoral head in the acetabulum. Quadratu ...

– L4 to S1.

Etymology

Gemellus is the diminutive of "geminus" meaning twin, doubled or duplicated. The superior and inferior gemellus muscles are paired and perform the same action.

Additional images

File:Superior gemellus.jpg, Superior gemellus muscle. File:Gray235.png, Right hip bone. External surface. File:Gray244.png, Right femur. Anterior surface.

References

External links

*
PTCentral

Univ. of Wash. Radiology
{{Authority control Hip muscles Hip lateral rotators Deep lateral rotators of the hip Muscles of the lower limb