Biomechanics of the human epiglottis.

The mechanism that folds the epiglottis down over the closed larynx in the course of swallowing has been unclear. Measurements of the force needed to fold the epiglottis in cadaver specimens exceed the estimated force available from the aryepiglottic muscle. Frame-by-frame analysis of cinefluorograms reveals that deglutitional epiglottic downfolding occurs at the time of maximal elongation of the hyoepiglottic ligament. The observations lead us to propose a conical model of epiglottic downfolding which also explains the conical shape of the epiglottis usual in early infancy. The infant shape may be part of a protective partially closed entrance adaptive to suckling, while maturational widening of the opening adapts to the growing respiratory demands of increasing physical exertion.