The muscular tissue of the vestibular folds was investigated in plastinated serial sections of 32 normal adult larynges. Three muscular systems could be distinguished. A posterolateral muscle layer was found to be developed at the lateral margin of the posterior part of the vestibular fold. Its fibers extended in a sagittal direction, and their contraction probably resulted in an adduction of the entire tissue of the vestibular fold towards the midline. Within the anterior part of the vestibular fold, an anterolateral muscle sheet was seen to attach to the thyroid cartilage. An anteromedial muscular system consisted of scattered groups of muscle fibers situated medially and dorsally to the laryngeal ventricle and saccule. These fibers were presumed to exert a downward pressure on the vestibular folds, in addition to an adductor function. According to clinical experience, adductor movements of the vestibular folds can be trained, even in cases with a recurrent laryngeal nerve lesion, in order to produce a compensatory voice. Thus, the muscles of the vestibular folds are probably innervated by the superior laryngeal nerve.

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The precise topographic relationships of the paraglottic space (PGS) were investigated in serial plastinated or frozen whole-organ sections of 46 normal adult larynges. Laterally, the PGS was bordered by the thyroid cartilage. Superomedially, the PGS in some specimens was only separated from the periepiglottic space by a coherent collagenous fiber septum. The paraglottic adipose tissue extended between the caudal fibers of the thyroarytenoid muscle. Inferomedially, the PGS was bordered by the conus elasticus. The anteroinferior portion of the PGS extended beyond the larynx beneath the inferior rim of the thyroid cartilage. Posteroinferiorly, the paraglottic adipose tissue extended towards the cricoarytenoid joint. Dorsally, the PGS was bordered by the mucosal lining of the piriform sinus. Due to the intimate topographic and histologic relationships present, cancer involving the PGS may rapidly infiltrate all adjacent anatomic structures.

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.

The aryepiglottic folds extend between the arytenoid cartilage and the lateral margin of the epiglottis on each side and constitute the lateral borders of the laryngeal inlet. They are involved in physiologic closure mechanisms of the larynx and in pathologic conditions such as inspiratory stridor. Information on the normal topography of the aryepiglottic folds is poor and controversial. Therefore, this region was reinvestigated in serial whole‐organ sections of 25 plastinated normal adult human larynges. Dorsally, the right and the left aryepiglottic folds are separated by the interarytenoid notch and comprise the corniculate and cuneiform cartilages, as well as numerous groups of mucous glands. Ventrally, the aryepiglottic folds are adjacent to the peri‐epiglottic adipose tissue. Both regions are clearly separated by several layers of transversely oriented collagenous fiber layers. The muscular constituent of the aryepiglottic folds is only poorly developed, and no muscle fibers insert at the epiglottis. A coherent quadrangular membrane representing a ligamentous “skeleton” of the aryepiglottic folds is absent. A conspicuous collagenous fiber layer is found only to strengthen the free dorsal margin of the fold. Both muscular and ligamentous components may render the aryepiglottic folds sufficiently tense as to resist inspiratory inward suction in normal cases. However, pliability must be preserved to guarantee adequate folding in approximation of the aryepiglottic folds during deglutition. Thereby, the posterior part of the laryngeal inlet is closed, whereas the anterior part is probably closed by independent inward bulging of the peri‐epiglottic adipose tissue. Clin. Anat. 11:223–235, 1998. © 1998 Wiley‐Liss, Inc.