Morphologic correlates of physiologic closure mechanisms of the laryngeal vestibule were investigated in plastinated serial sections of 25 normal adult larynges. The anterior part of the laryngeal vestibule was seen to be bounded by the epiglottis and the thyroepiglottic ligament medially, and by lateral extensions of the periepiglottic adipose tissue laterally. The posterior part of the laryngeal vestibule was bordered by the aryepiglottic folds. Morphologically, the periepiglottic space and the aryepiglottic folds were completely separated by several transversely oriented collagenous fiber layers attached to the thyroid perichondrium laterally. This may suggest a corresponding functional separation, as described previously in the literature. Closure of the anterior part of the laryngeal vestibule during swallowing is probably related to the lowering of the epiglottis, with both depending on pressure exerted onto the periepiglottic adipose tissue. Closure of the posterior part of the laryngeal vestibule is most likely related to closure of the rima glottidis, with both depending on adduction of the arytenoid cartilage.