Asymmetry of the laryngeal framework: a morphologic study of cadaver larynges

Asymmetry of the laryngeal framework was investigated with 50 excised human larynges, ten from newborns (five males, five females), 20 from adults in their 20s (ten males, ten females), and 20 from adults in their 50s (ten males, ten females). All adults were right-handed. The results are summarized as follows. 1) The laryngeal framework was asymmetric to a greater or lesser extent in all larynges. 2) The degree of asymmetry did not differ among different age groups or between sexes. 3) In newborns, there was no directional preponderance in asymmetry. 4) In older adults, there was a directional preponderance in asymmetry. The right thyroid lamina tended to tilt laterally whereas the left lamina showed a tendency to tilt medially. The right cricoarytenoid joint tended to be located slightly more laterally, posteriorly, and inferiorly than the left joint. The longitudinal axis of the thyroid cartilage was inclined to shift to the right posteriorly against the axis of the cricoid cartilage. The thyroid cartilage as a whole tended to tilt to the right against the cricoid cartilage. 5) There must be some compensatory mechanisms for the asymmetric framework to keep the vocal fold edges relatively symmetric.