[Supernumerary muscle on the dorsal surface of the hand. A case report].

The authors report a case of a painful wrist related to a "Manieux muscle" of the dorsal aspect of the hand. Manieux muscles are very rare supernumerary muscles first described by anatomists at the beginning of the 20th century. To our knowledge no symptoms related to this condition have been previously reported. In the present case, symptoms were limited to pain in the wrist with the presence of a fluctuant tumor. The putative diagnosis was synovial cyst. The abnormal muscle was revealed at operation. The operative findings confirmed the responsibility of the Manieux muscle for the patient's symptoms. The muscle was totally resected and pain completely disappeared without any functional impairment.