EFFECT OF THE SPHINCTERIC ACTION OF THE LARYNX ON INTRA-ABDOMINAL PRESSURE: AND ON THE MUSCULAR ACTION OF THE PECTORAL GIRDLE

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A STUDY OF THE LITERATURE ESTABLISHES THE FACT THAT THE LARYNX CAN UNDERGO A SPHINCTERIC CLOSURE  The function of the larynx is by no means limited to its role in the production of voice. Perhaps of even greater importance, at least from the standpoint of the physiologist, is its action as a sphincter functionally separating the upper from the lower respiratory passages. This action was recognized long ago. Wyllie,¹ for instance, in 1866 pointed out that closure of the glottis takes place as a sphincteric phenomenon under three circumstances, i. e., during phonation, during deglutition and when air is compressed in the lungs and trachea whether voluntarily or involuntarily, as before each act of coughing. Wyllie apparently was not the first to make such observations, for he referred to "Mayo's Physiology," which I have been unable to trace. In addition, Czermak² five years before him described approximation of the