Following the attempt to arrange a clear description of the physical characteristics of blunt thoracic trauma, the morphological findings of a case of traumatic ventricular septum defect with interventricular and atrioventricular communications is presented in detail. Accepting the principle that the occurance of a traumatic defect in the ventricular septum without a previous lesion of the myocardial texture is highly improbable, a embryologic based theory of the formal genesis of traumatic ventricular septum defects, in sense of a “Pathoklise”, is reviewed. The formal relationships between (1) “high-seated” traumatic ventricular septum defects (type I) and congenital heart anomalies following alteration of the vectorial bulbus turn and, (2) between the purely muscular, apical traumatic ventricular septum defects (type II) and connatal interventricular communications at “atypical location” are demonstrated.