Untersuchungen zur Bedeutung der extralaryngealen Muskulatur für den Phonationsakt unter besonderer Berücksichtigung des Musculus cricopharyngeus

Summary

Within the interplay of the muscular function systems of the larynx during phonation, the musculus cricothyreoideus and the musculus cricopharyngeus create a partnership which also in the human can be recognized as the original external larynx sphincter construction. Anatomic examinations of the musculus cricopharyngeus showed its division into four distinguishable parts, with more or less a fanshaped distribution and in part internally interlacing with the fibres of the other side, with the musculus cricothyreoideus, the pharynx basal membrane, the levatores oesophagi muscles as well as the uppermost section of the oesophagus ring musculature, through which a horizontal displacement of the cricoid cartilage and of the thyroid cartilage against one another during the isometric contraction of this muscle is made possible and thus a more favorable pre-condition is created for the trajectory motion of the fibres of the musculus cricothyreoideus in the sense of a long-handle lever in the vocal cords. This effect, which is even much more clearly recognizable in primates, because of the peculiarities of the glottis construction, was exhibited in comparative anatomical investigations; its validity with regard to humans during clinical observations was explained; it was demonstrated by means of electric stimulation experiments in animals and electro-myographic readings in humans. Thus a synergic or auxillary function of the musculus cricopharyngeus may be viewed as assured, in contrast to previous conceptions, for the dynamic action of musculus cricothyreoideus—musculus cricopharyngeus during the act of phonation. The function is, then, always effective, as soon as a special demand is put on the voice.

Zusammenfassung

Innerhalb des Zusammenspieles der muskulären Funktionssysteme des Kehlkopfes beim Phonationsvorgang bilden der M. cricothyreoideus und der M. cricopharyngeus eine Gemeinschaft, die auch beim Menschen noch den Bau des ursprüngglichen äuβeren Kehlkopfsphincters erkennen Jäβt. Anatomische Untersuchungen des M. cricopharyngeus zeigten dessen Unterteilung in vier Portionen unterschiedlicher, annahernd fächerförmiger Verlaufsrichtung and zum Teil innige Verflechtung mit den Fasern der Gegenseite, mit dem M. cricothyreoideus, der Pharynxgrundmembran, den Mm. levatores oesophagi Bowie dem. obersten