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Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: G:

Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: G

Gemelli and Obuturator Internus

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD

Peer Review Status: Internally Peer Reviewed

The gemelli vary in size. The superior gemelus may be small or absent, or may be doubled and may insert into the capsule of the hip joint.

The inferior gemellus may also be doubled; its absence has also been reported but more rarely than the superior muscle.

Terry reported that the superior gemellus was absent, on one side or both, in 31 of 254 cadavers. Wood reported the superior gemellus was absent in 4 of 70 bodies, three male and one female. Nakano found no gemelli absent, in Chinese bodies, in 75 body halves. Adachi could find no case of the superior gemellus being absent in 207 lower limbs of Japanese.

In very rare cases, both gemelli (superior and inferior) may be absent. The superior gemellus may be fused with piriformis or gluteus minimus, and the inferior gemellus with quadratus femoris. Both are frequently, more or less continuous with the obturator internus.

The obturator internus muscle is not subject to much variation. Its absence has been reported and complete division into two parts , as well as accessory slips, have been noted.


Adachi, B. (1909-10) Beiträge zur Anatomie der Japanes. Zeitschr. Morophol. Anthropol. 12:261-312.

Anson, B.J. Ed. (1966) Morris' Human Anatomy,12th ed., The Blakiston Division, McGraw-Hill Book Company. New York.

Gruber, W. (1878) Ein Musculus obturator internus biceps. Arch. Path. Anat. Physiol. Klin. Med. 73:348-350.

Gruber, W. (1884) Mangel beider Musculi gemelli bei Anwesenheit des Obturator internus. Arch. Path. Anat. Physiol. Klin. Med. 95:180-183.

LeDouble, A.F. (1897) Traité des Variations du Système Musculaire de l'Homme et Leur Signification au Point de l'Anthropologie Zoologique., Libraire C. Reinwald, Schleicher Freres, Paris.

Macalister, A. (1875) Observations on muscular anomalies in the human anatomy. Third series with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci. 25:1-130.

Nakano, T. (1922-23) Beiträge zur Anatomie der Chinesen. Okajimas Folio Anat. Jpn. 1:274-282.

Terry, R.J. (1942) Absence of superior gemellus muscle in American Whites and Negros. Am. J. Phys. Anthropol. 29:47-56.

Wood, J. (1867) On human muscular variations in their relation to comparative anatomy. J. Anat. Physiol. 15:44-59.

Wood, J. (1868) Variations in human myology observed during the winter session of 1867-68 at King's College, London. Proc. Roy. Soc. Lond. B 17:483-525.

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