Conclusions

Abstract

The development of muscles of the palm and sole as well as of muscles and tendons in the dorsum manus and pedis proceeds in course of ontogenesis in loco. The muscle primordia originate from the blastemas which are situated approximately in the places of definitive muscles from the beginning of their differentiation. No signs of a real migration of muscular primordia, as claimed e.g. by Ruge (1878a), are found. The positional changes of muscular primordia evidently occur only by a differential growth of the skeleton and musculature and by mutual growth differences of single muscle primordia. The actual growth, however, was not measured in this study, but evident gradual changes in the relative size of single formations were observed from stage to stage together with a gradual transition of these changes in size into changes of mutual position. These changes of position, however, are never so great as formerly implied. A gradual differentiation of a further formation can also take part in this process. Ruge (1878a), for example, described the migration of the interossei primordia from the palmar side into intermetacarpal spaces. It is true that at the beginning of development these primordia are found palmar to the intermetacarpal spaces and later also inside them (but also palmar to the spaces). In fact, no immigration of primordia into intermetacarpal spaces is here in question, but the gradual differentiation and fusion of the flexores breves profundi primordia (situated palmar from intermetacarpal spaces) with a further intermetacarpal primordium which had differentiated in the meantime inside the space.