Dealing with structural pathology we have to localize it and to determine its nature. Dealing with dysfunction of the locomotor system we are mainly concerned with the disturbed correlations and interplay of numerous, but reversible lesions. Treatment may therefore appear easy at first sight, but it is frequently very complex. Dysfunction affects the entire motor system to a certain extent, forming chains of lesions: we therefore have to diagnose the entire chain and to determine its most relevant links. Some of the most important chains are described. It is shown that these chains can be best explained by the development of erect posture during the first three months of infancy. The most important feature is the co-contraction pattern of agonist and antagonists which is essential for the stabilization of bipedal posture.

        Key words: muscular co-contraction, chain reactions, trigger points, development of bipedal posture