Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: E
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
The tendon of insertion is sometimes divided and gives a slip to the fourth digit. An ulnar slip has been observed to end on the base of the fifth metacarpal, thus exactly reproducing the arrangement of the serially homologous slip known as peroneus tertius in the leg. The muscle may be absent in rare cases, but fusion with extensor digitorum is frequent, in which case the tendon comes from the common extensor.
Mori has described an extensor digiti minimi accessorius which occurs when the extensor digiti minimi divides into two slips. The ulnar part extends onto the back of the fifth metacarpal to the base of the first phalanx of the little finger and is the extensor digiti minimi, the radial slip extends to the dorsal carpal ligament and inserts into it and this becomes the extensor digiti minimi accessorius. Mori found this variation in 4% of his subjects. Mori also describes an extensor digiti minimi et quarti, which is present in 2% of his subjects. The terminal tendon of extensor digiti minimi divides into two slips, one extends over the fifth metacarpal to insert onto the proximal phalanx of the little finger, and second slip extends over the fourth metacarpal and fuses with the terminal tendon of extensor digitorum for the fourth finger.
Macalister reported the following variations:
Syn.: m. Extensor digiti quinti proprius.
Extensor Digiti Quinti Proprius Muscle Tendon Supplies Both the
Fourth and Fifth Digits.
(Vesalius, Fabrica, 1543), from Straus, Jr. and Temkin.
Baumann, J.A. (1947) Valeur, variation, et équivalences des muscles extenseurs, interosseux, adducteurs et abducteurs de la main et du pied chez l'homme. Acta Anat. 4:10-16.
Calori, L. (1867) Di alcune varieta muscolari dell'avambraccio e dell'eminenza ipothenar. Mem. R. Accad. Sci. Istituto di Bologna. S.2, 7:359-381.
Flower, W.H. and J. Murie. (1867) Account of the dissection of a Bush woman. J. Anat. Physiol. 1:202-208.
Gruber, W. (1885) Zweibäuchiger Extensor digiti V proprius manus mit Insertion eines seiner Bäuche an die Basis des Metacarpal V, und die ihm homologe Variante des Peroneus III. Arch. Path. Anat. Physiol. Klin. Med. 99:480-483.
Gruber, W. (1885) Absoluter Mangel des Extensor digiti quinti proprius manus bei mangel seiner Vagina im ligamentum carpi dorsale: ganz ausnahmsweise und nur beim Menschen (2 Fall) bei Vorkommen des muskels dennoch Mangel der Vagina constant bei den Prosimiae. Arch. Path. Anat. Physiol. Klin. Med. 99:484-488.
Gruber, W. (1885) Duplicität des Musculus extensor digiti quinti et quarti proprius manus. Arch. Path. Anat. Physiol. Klin. Med. 101:260-262.
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.
Mori, M. (1964) Statistics on the musculature of the Japanese. Okajimas Fol. Anat. Jap. 40:195-300.
Straus, Jr., W.L. and O.Temkin. (1943) Vesalius and the Problem of Variability. Bull. History Med. 14:609-633.
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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