[The frontomaxillary suture. Theoretical bases and general principles of the application of postero-anterior extraoral forces to the orthopedic mask].

Each maxilla is joined to the frontal bone by a veritable fronto-maxillary sutural joint which, in the young subject, permits sliding movements. During growth, the maxilla orients itself in relation to the mechanical effects of the various structures which surround it. The location, below the frontal sinus, of this joint endows it with special properties of resistance and change in position of orientation. These anatomico-functional peculiarities explain certain results obtained by classical heavy antero-posterior of postero-anterior extra-oral forces.