The anterior commissure of the human larynx revisited

The anterior commissure (AC) of the human larynx is usually understood as an area of the glottis anteriorly situated between the two vocal folds inserting to the thyroid cartilage (TC). The pattern of spread of AC carcinoma could hypothesize that AC could include other structures of the ventral larynx as developmental anatomy could demonstrate.

Ten adult larynx specimens from donation program cadavers and 15 selected fetal specimens (from 11 to 34 weeks of amenorrhoea) were studied using microdissection and histological serial sections stained with hematoxylin-eosin and reticuline.

In adult specimens, internal perichondrium of the TC was easily detached from the entire lateral lamina but not from an intermediate lamina superiorly marked by the superior thyroid notch. On this median band of TC is inserted the ventral connective tissue of the three levels of the larynx: the ventral part of the vocal folds with the anterior macula flava, the Broyle's epiglottic ligament, and the subglottic part of the conoid ligament. In young fetuses (11-12 weeks), intermediate lamina of TC joined at the glottic level but not at the supraglottic level; in fetuses at 22-25 weeks, a meshwork of bundles of connective fibers inserted to the intermediate lamina of TC. In fetuses at 33-34 weeks, organization is practically identical to adult specimens.

According to the adult anatomical features and the organogenesis, the AC of the human larynx could be anatomically defined ventrally as being made up of the intermediate lamina of TC beneath the superior thyroid notch and dorsally the ventral insertions of vocal folds with macula flava, supraglottic Broyle's ligament, and subglottic conoid ligament leading to a "developmental" AC definition which could better explain specific spreading of AC carcinoma.