[The existence of M. peroneus digiti IV and of M. peroneus digiti V in the distant predecessors of man].

Recent evolutionary myological researches on the m. peroneus digiti IV and m. peroneus digiti V in Man have shown that these muscles had been at first an inseparable component of his peroneal musculature. The above mentioned muscles have undergone practically a full reduction in the course of man's phylogenesis. The peroneal muscular group of the pelvic limb of the Mesocricetus auratus consists now of m. peroneus longus, m. peroneus brevis and both m. peroneus digiti IV et m. peroneus digiti V. In other words, the situation is the same as in the Prosimia. The comparasion of the organogenesis of the muscles in question in Man and in the golden hamster shows that the morphology and topography of their primordia on the proximal parts of the metatarsus in the Man's embryo of 14 mm CRL are the same as in the embryo of Mesocricetus auratus of 11 d and 18 h. The development of this common primordium is different after that age of the embryos of both mammalian species. It reduces and usually completely disappears in Man, while in Mesocricetus auratus it gives rise of the tendons of the m. peroneus digiti IV and the m. peroneus digiti V. Thus the present research proves that the primordium in the proximal parts of the metatarsus of Man's embryo with 14 mm CRL is a tendo-forming plate of the tendons of the m. peroneus digiti IV and m. peroneus digiti V.