Showing papers in "American Journal of Physiology in 1907"

The mechanical effects produced by the contraction of individual muscles of the thigh of the frog

Abstract: M ANY years ago one of the writers of this paper attempted, under the guidance of Professor Carl Ludwig, to determine the method of spread of reflex processes in the spinal cord of the frog? In the course of this work he was compelled to recognize that many of the movements of the hind limb of the frog which have the appearance of being the result of finely adjusted nervous coordinations , are really due to the mechanical conditions under which the muscles act on the bones. The lesson was forced home, that before we can arrive at reliable conclusions as to the method of action of the central nervous mechanisms concerned in reflex actions, we must obtain a clear picture of the mechanics of the limb itself. In a recent paper 2 it has been shown that not only the effectiveness of the contraction of a given muscle alters with the gain and loss of leverage which comes as the bones have their position changed, but that the character of the movement which a given muscle may produce may be greatly altered, indeed in some cases reversed, by a change in the relative positions of the bones on which the muscle in 1 Die raiimliche und zeitliche Aufeinanderfolge reflectorisch cor,trahirter muskeln. Archiv fiir Anatomic und Physiologic, I%;, p. 405. 2 \" The tendon action and leverage of two-joint muscles of the hind lee of the frog with special reference to the spring movement. \" Contributions