# Sexual Dimorphism and Age-Related Structural Changes in the Human Larynx: A Morphometric Study with Histological Correlates Relevant to Voice and Diagnostic Assessment

## TL;DR

This study examines how the human larynx changes with age and differs between sexes, providing insights for voice evaluation and diagnosis.

## Contribution

The study identifies age-related qualitative structural changes in the larynx, distinct from sex-based morphometric differences.

## Key findings

- Male larynges are significantly larger in anteroposterior length, thyroid cartilage height, and glottic area compared to females.
- Cartilage calcification increases markedly after age 60 and is independently predicted by age, not sex.
- Histology shows age-related muscle atrophy and reduced collagen and elastin density in vocal folds.

## Abstract

Background/Objectives: The human larynx exhibits marked sexual dimorphism and undergoes age-related structural remodeling, both of which influence voice characteristics and have important implications for diagnostic assessment. While sex-related differences in laryngeal size are well recognized, the extent to which aging contributes to dimensional versus qualitative structural changes remains incompletely defined. This study aimed to analyze sex- and age-related morphometric and histological characteristics of the human larynx, with a focus on features relevant to voice evaluation and diagnostic interpretation. Methods: A cross-sectional anatomical study was conducted on 80 cadaveric human larynges preserved in 10% buffered formalin. Specimens were stratified by sex and age (<30, 30–60, and ≥60 years). Direct morphometric measurements included anteroposterior laryngeal length, thyroid cartilage height, thyroid angle, and relative glottic area. Epiglottic morphology and the presence of laryngeal cartilage calcification/ossification (binary classification: present vs. absent) were recorded. Histological analysis of vocal fold tissue was performed on a stratified subset of specimens. Statistical analysis included t-tests, chi-square tests, two-way ANOVA, effect size estimation, and logistic regression. Results: Male specimens showed significantly greater anteroposterior length, thyroid cartilage height, and relative glottic area, along with a narrower thyroid angle, compared with females (all p < 0.001), with large effect sizes. Age did not significantly influence overall laryngeal dimensions. In contrast, cartilage calcification/ossification increased markedly after the age of 60. Logistic regression identified age ≥ 60 years as the only independent predictor of calcification (OR = 4.37, p = 0.039), while sex was not significant. Epiglottic morphology demonstrated a sex-dependent distribution. Histology revealed age-related muscle atrophy and reduced collagen and elastin density. Conclusions: Sex defines the baseline morphometric framework of the adult larynx, whereas aging, particularly beyond 60 years, drives qualitative structural degeneration. These findings provide a reproducible anatomical reference for distinguishing sex-related variation from age-related changes in diagnostic assessment.