[The lingual bone of the human mandibular symphysis (author's transl)]

Study of sections in the three sagittal, frontal and horizontal planes in the chin region of the newborn has shown the existence of an adaptive growth centre consisting of secondary cartilage situated at the anterior extremity of the two hemimandibles. These two zones of secondary cartilage are in continuity with the interosseous fibrous connective tissue of the chin (itself continuous with the mandibular periosteum) into which the genioglossal and geniohyoid muscles are inserted posteriorly and the digastric muscles anteriorly, at the site of the anterior and inferior ossicles. At 15 months, synostosis is not complete but there would seem to be a zone of bone growth posteriorly, at the site of the insertion of the genioglossal muscles.