The superficial human digital flexor and extensor are rich in terminal sensitive apparatuses and they present peculiar reflexogenic zones. There is not any essential difference between these muscle-antagonists according to the topography of the receptors, but functionally different muscle areas (both in the superficial digital flexor and in the digital extensor) are not equally provided with the receptory apparatuses. In the course of development, the number of sensitive terminals in the proximal and distal portions of the muscles is increasing. An absolute number of the receptors is much greater in the digital superficial flexor than in the digital extensor, nevertheless, this difference per 1 g of mass disappears; that can be evidently connected with complexity and differencity of movements which the upper extremities perform.