Adductor Hallucis, Caput Obliquum
A slip has been observed passing from this muscle to the base of the first phalanx of the second or even the third toe. It may be attached to the opponens or to the lateral head of flexor hallucis brevis. It is of theoretical interest when this head is considered as a separate muscle fasiculus because it may represent a vestige of a plantar adductor of the second toe. A slip from the adductor is occasionally found ending on the metatarsal bone of the great toe. It may arise entirely from the sheath of the long peroneal tendon.
Another variant, flexor brevis digiti II (pedis), arises from the plantar aspect of the base of the fourth metatarsal adjacent to adductor hallucis and inserts into the capsule of the second metatarsophalangeal joint.
In eleven subjects with hallux valgus (18 feet studied), all 18 had an anomalous tendon that joined tibialis posterior with the adductor hallucis muscle.
Syn.: m. Adducteur hallucis (Cruveilhier).
References
Baumann, J.A.. (1947) Valeur, variation, et équivalences des muscles extenseurs, interosseux, adducteurs et abducteurs de la main et pied chez l'homme. Acta Anat. 4:10-16.
Gunal, I., Sahinoglu,K., and R.A.Bergman. (1994) Anomalous tibialis posterior muscle as an etiologic factor of hallux valgus. Clin. Anat. 7:21-25.
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Hepburn, D. (1893) The adductor muscles of the thumb and great toe. J. Anat. Physiol. 27:408-410.
Kaplan, E. B. (1955) The tibialis posterior muscle in relation to hallux valgus. Bull. NY Hosp. Joint Dis. 16:88-93.
Macalister, A. (1875) Additional observations on muscular anomalies in human anatomy (third series), with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci. 25:1-134.
Toldt, C. (1928) An Atlas of Human Anatomy for Students and Physicians. The Macmillian Company, New York.