Extensor Digitorum Longus (pedis)

Variations in this muscle relate mainly to the origin and arrangement of its various tendons. They may be doubled, or extra slips may arise from one or more tendons to their corresponding metatarsal bones, to the short extensor, or to one of the interosseous muscles. A slip to the great toe from the innermost tendon has also been seen. In contrast to the corresponding tendons in the hand, all are independent of their neighbors; their are no connecting bands between them. The muscle belly supplying the fifth toe may be reinforced by peroneus tertius and it may also contribute to extensor hallucis longus or extensor hallucis brevis. An EDL muscle was found with three tendonous slips for the second, third, and fourth toes according to Sirasanagnadla, et al.

Macalister reported the variations for this muscle as follows. Extensor digitorum longus: 1. May send a slip to the base of the first phalanx of the second toe (Wood); 2. Or a connecting slip from its innermost tendon to the extensor hallucis; 3. The tendon for the little toe may arise by a special belly with peroneus tertius (Wood); 4. A doubled tendon for the little toe; 5. Or for the second toe; 6. To the base of the first phalanx of the second toe; 7. A slip to the first interosseous muscle; 8. Slips from this muscle and peroneus tertius to the anterior end of the fifth metatarsal bone; 9. A slip from the second tendon of the long extensor to the short muscle; 10. A special belly for each tendon (Wood); 11. The same with two slips from peroneus brevis to the outer (lateral) division; 12. Slips from the tendon for the fourth and fifth toes inserted respectively into the fourth and fifth metatarsal bones (Wood); 13. The outermost tendon of the longus has been found joined to that of the brevis by a cross band (Wood); 14. A slip to the fifth metatarsal coexisting with the peroneus tertius; 15. This muscle was found by Ringhoffer, in a case of a deformed limb, with four tendons, one to the second toe, one to the fifth, and two to the fourth toe. Wood examined 70 extremities and found a tendon three times that left extensor digitorum longus and inserted onto the middle of the base of the fifth metatarsal. A slip from extensor digitorum longus may join the tendon of extensor hallucis brevis.

Syn.: m. extensor digitorum pedis longus, extensor dig. comm. long.

Riferimenti dell’opera originale

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• 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.
• Bhadkamkar, A.R. and V.R. Mysorekar. (1961) Anomalous peroneus tertius and extensor digitorum longus muscles. J. Anat. Soc. India 10:37-38.
• Gruber, W. (1875) Über den Musculus extensor digitorum communis manus anomalous mit 5 Sehnen zu allen Fingern, und uber den Musculus extensor digitorum longus pedis anomalous mit 5 Sehnen zu allen Zehnen. Arch. Anat. Physiol. Wissen Med. 1875:204-210.
• Gruber, W. (1875) Ein Musculus extensor digiti II pedis longus. Arch. Path. Anat. Physiol. Klin. Med. 65:23-25.
• Gruber, W. (1888) Theilung der vagina am Ligamentum der fascia cruralis in der Fussbeuge in zwei secundäre Vaginae für den Musculus extensor digitorum longus pedis bei dem Menschen und bei Säugethieren. Arch. Path. Anat. Physiol. Klin. Med. 114:371-374.
• Henle, J. (1871) Handbuch der Muskellehre des Menschen, in Handbuch der systematischen Anatomie des Menschen. Verlag von Friedrich Vieweg und Sohn, Braunschweig.
• Shigematsu, M., Tsubakihara, M. and S. Maruyama. (1956) On the M. extensor digitorum longus. Kurume Igakkai Zasshi. 19:1297-1302. In Japanese.
• Sirasanagndla, S.R., Bhat, K. M. R., Nayak, S.B., Shetty, P. and R. Thangarajan. A Rare Case of Variant Morphology of Peroneus Tertius Muscle. (2014) J. Clin Diagn Res. 8(10):AD01-AD02.