[Mechanism of hernia of the groin].

Utilitarian aspects of hernia pathogenicity are envisaged to assist comprehension of surgical gestures, the choice of effective techniques and the abandon of those which are not and may be of medicolegal interest: all inguinal hernias are due to parietal weakness. Anatomical factors are studied based on data from dissection, from in front backwards and then from behind forwards, from which certain major notions are drawn: that of role of transverse fascia in imperviousness to intra-abdominal pressure; that of uniqueness of inguinal hernias, all of which cross the transverse fascia in the region of the regional osteomuscular framework; that of the necessary degradation of musculofascial plane for a hernia to develop, with as a corollary the need for inguinal imperviousness at the transverse fascia level to be restored. Factors may be present that increase the "natural weakness" of the groin: anatomical variations affecting inguinal triangle; biological disorders affecting inguinal structures (aponeurotic and fascial senescence, collagen diseases, musculo-tendino-aponeurotic dystrophy). A breakdown in mechanisms of protection against increased intra-abdominal pressure promoted a summary of features defining intra-abdominal pressure under physiologic conditions and classical herniogenic circumstances. A summary of pathogenic mechanisms of inguinal hernia is presented while emphasizing the two principal theories: the saccular theory and that of musculo-fascial weakness, with their consequences for choice of therapies to be opposed to the polymorphism of hernial lesions.