Anatomy of the duplicated manus of the calf
Nasu, T. (Miyazaki Univ. (Japan). Faculty of Agriculture) | Nakai, M. | Fukumoto, K. | Hayashi, A.
The left forelimb of a male co-twin calf (two days old) was dissected. The results of morphological observations are as follows: The left forearm was shorter and degenerated as compared to the right one. The trochlea of the humerus and head of the radius were fused together thus the elbow joint could not be moved. At the carpal joint, the manus was strongly flexed medially, so the hoof could not make contact with the ground. The manus was duplicated; two large metacarpal bones (Mc III + IV) arranged dorsoventrally were fused at the central part of the bodies. Both metacarpuses were articulated with the distal row of one carpus. The forearm was not as long as the normal right one. The carpal joint was flexed and the muscles that extended along the antebrachium appeared to be fused together. The origins and insertions of these muscles were obscure. The extensor and flexor muscles of the digits run to the ventral manus. In addition to these muscles, the digits of the ventral manus were supplied with the radial artery, palmar branch of cranial interosseus artery and the ulnar nerve. Thus the dorsal manus may be a parasitic limb arising from mutation in one of the twins that were fused at the carpusShow more [+] Less [-]
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