Deformation of the chest wall during breathing efforts

chest wall during hea thing efforts. J * A ppl. Physiol. 2 3: (6) : 182 7-1832. rg66-The deformation of the chest wall during static respiratory efforts and during different pattern of breathing cycles have been studied by measuring the dorsoventral and lateral diameters of the rib cage. During inspiratory efforts the horizontal section of the rib cage becomes more elliptical, whereas during expiratory efforts it becomes more circular. During hyperventilation or breathing through resistances the change of the dorsoventral diameter lags behind that of the lateral one and that of the lung volume. The phase shift in-creases as the load increases. Hence the force of the respiratory muscles acts mainly on the lateral part of the rib cage, whereas the frontal part is mainly driven by the pressure across it and by the movement of the lateral parts. The deformation occurring under load implies theoretically that: a) some muscles