(in french)Over the last two years, an increasing interest has been turned on the ventilation mechanisms. Severalresearches have underlined the need for a reliable, non-invasive three-dimensional (3D) technique toassess the action of the muscles of the inspiratory pump and more particularly the diaphragm.In this context, modelling has a crucial place as an approach permitting the synthesis and theintegration of physiological data in order to reproduce and predict motions and distortions of allmodelled anatomic structures.In this internship, we present and study a 3D functional model of the diaphragm muscle allowing formotion quantifications based on a functional diaphragm representation. We have used data came fromdynamic IRM images segmentation and we have considered several simplified geometrical models ofthe diaphragm in order to illustrate mechanical aspects of the contraction, assess our modellingmethod and reproduce the piston motion of the diaphragm.The final model provides geometrical information (diaphragmatic areas distortions and calculation ofvolumes) and dynamic (muscular activity and activation signal).This work shows the adequacy of our modelling method in regard to our problematic and brings outimportant aspects that should be considered in future works towards a more sophisticated model of thediaphragm.