RESUMEN
Located at the center of the neck and the pharyngeal column and, thanks to its attachments, tied to the base of the skull, to the mandible, to the tongue, to the larynx, and to the scapular belt, the hyoid bone is intimately related to an extensive tendino-muscular complex. From this strategic position, the hyoid bone participates in all functional and nutritional activities of the oro-facial complex. Heavily involved in the physiology of the pharyngeal column, it appears to enjoy a remarkable stability in relation to its surrounding structures as it participates in the critical process of vertical ontogenetic development. Deceptively simple in its shape and location it is anything but. While it would be easy to scorn it as a vestigial organ of little importance, the hyoid bone is actually an ancient witness of the evolution of the first human vertebrae and a vestige of the 2nd and 3rd brachial arches. Like a toy buffeted by powerful groups of muscles and tendons, the hyoid bone occupies a crossroads position where it is solicited by many vital functions, the most critical of which is respiration. Its functional behavior seems to have evolved considerably over the course of phylogeny. By piecing together the conceptions of many authors, we can conclude that the similarities--and, later, the differences--existing between the human fetus and those of other primates, and, then between young children and young primates, are related to an essentially different status quo, which modifies the delicate equilibrium of the pharyngeal region. In metamorphosing from a sagittal equilibrium to one that is vertical, this very status quo maintains an open respiratory airway during each time frame, continuously permitting the articulation and modulation of sounds, particularly during the vertical period. The hyoid bone is unpaired, in a mid-line position, symmetrical, and located just below the mandible with which it shares, to an astonishing extent, certain morphological characteristics. Its maturation and its ossification occur slowly and late even though it migrates much more rapidly to a vertical position than does the bulk of the cervical complex. True articulations between the body and the horns of the hyoid bone persist for a very long time; and so the junction between the small horns doesn't fully calcify until about the age of 50; and, in spite of its appearance, the hyoid bone is extremely supple, a quality that allows it to make substantial contributions to functional activity. If the hyoid bone itself scarcely moves during normal respiration, modern research attributes an increasing role to it in the maintenance of the equilibrium of the pharyngeal column. It seems to be called upon to respond to a number of demands that it manages to satisfy as it helps to maintain the permeability of the pharyngeal column and thus make respiration possible. In so doing, the hyoid bone adjusts its positioning, and, perhaps most important, its orientation to the physiological requirements imposed by pharyngeal obstruction and mouth breathing. Intimately connected to the larynx, the hyoid bone plays a part in phonation that has long been recognized. Recent studies now also show that the contribution the hyoid bone makes to respiratory equilibrium is far more important than its small size would suggest.
Asunto(s)
Hueso Hioides , Dimensión Vertical , Adaptación Biológica , Adolescente , Adulto , Animales , Cefalometría , Niño , Preescolar , Femenino , Humanos , Hueso Hioides/anatomía & histología , Hueso Hioides/embriología , Hueso Hioides/fisiología , Lactante , Recién Nacido , Masculino , Desarrollo Maxilofacial , Músculos del Cuello/anatomía & histología , Músculos del Cuello/fisiología , Filogenia , Postura , Valores de Referencia , Respiración , Habla/fisiología , VertebradosRESUMEN
In dentofacial orthopedics, rehabilitation concerns the performance of the orofacial functions. Orthodontists will therefore speak of rehabilitation of functions, or functional therapy. Orofacial functions seem to obey a hierarchical system in accordance with their physiological importance; the impact of their disorders on both muscular behavior and facial morphogenesis, proportionally to their physiological importance. Therefore, priority will be given at a very early stage to the rehabilitation of respiration: restoring nasal ventilation is indeed an essential condition to obtain balanced oral functions because oral ventilation conditions both muscular posture and the performance of other functions. A little later, affective immaturity symptoms closely linked to various persisting bad suction habits will be looked after. At last, the rehabilitation of phonation and chewing both affected by the previous dysfunctions will participate in acquiring correct lingual position. The age for intervention will before all depend on the dysfunctional etiopathogeny. The morphological context, the importance of the malocclusion, and some orthodontic appliances also play a role in the the dysfunctional requests and the alterations of oral behavior.
Asunto(s)
Maloclusión/terapia , Terapia Miofuncional , Ortodoncia Interceptiva/métodos , Trastornos de la Articulación/terapia , Niño , Trastornos de Deglución/terapia , Humanos , Respiración por la Boca/prevención & control , Obstrucción Nasal/terapia , Aparatos Ortodóncicos Funcionales , Hábitos Linguales/terapiaRESUMEN
Cranio-facial dissymmetries especially concern orthodontics and orthognathic surgeons, but also all clinicians. A review of the conventional ways to study cranio-facial dissymmetries and their limits are presented. Progress of medical scanning allow to acceed to new methods of investigation and evaluation of cranio-facial morphology and dissymmetries. A cranio-facial dissymmetries analysis is suggested, based on CT, vestibular orientation, and an architectural and structural analysis, based on nervous indicators of the trigeminal nerve.