Mapping sex and age effects on thyroarytenoid and cricothyroid muscle structure and function.

The intrinsic laryngeal muscles are essential for voice production, airway protection, and the regulation of phonation. Among them, the thyroarytenoid (TA) and cricothyroid (CT) muscles play a key role in controlling vocal fold tension, length, and closure, thereby influencing pitch and voice quality. Despite their functional importance, age- and sex-related differences in these muscles remain partly understood. The present study aims to evaluate age-, sex-, and body size-related effects on the morphology of the TA and CT muscles and on the functional activity of the CT muscle in healthy adults. Morphometric analysis performed on 44 retrospectively collected neck MRI scans showed consistent age-related decline of the TA muscle across all measured dimensions, whereas the CT muscle demonstrated a more selective pattern, with age independently associated with thickness and volume but not with length or height. Functional assessment of the CT muscle conducted with electromyography (EMG) analyses of 29 healthy volunteers showed higher CT activation amplitudes in females, while increasing age was independently associated with lower activation amplitudes, higher resting amplitude, and longer return-to-rest time. These complementary observations suggest that intrinsic laryngeal muscles may not respond uniformly to aging: the TA muscle appears to demonstrate a more generalized age-related morphological decline, whereas the CT muscle exhibits more selective structural changes, while its functional activity shows age- and sex-related differences. Although derived from independent cohorts, these findings suggest that age-related voice changes may reflect muscle-specific alterations in laryngeal structure and neuromuscular performance, influenced by biological factors rather than a uniform aging process.