Regional variations and sex-related differences in human tracheal ligaments

Abstract

This study aimed to investigate the characteristics of the ligaments present between the thyroid, cricoid, and tracheal cartilages on living human bodies and cadavers using a digital palpation device. The mean dynamic stiffness values of the cricothyroid ligaments were 622.0 ± 88.2 N/m (mean ± SD) for humans, 956.1 ± 75.0 N/m when measured directly in the cadavers, and 826.5 ± 105.7 N/m when removed from the cadavers. There was no significant difference in dynamic stiffness between the cricothyroid and the first annular ligaments. The dynamic stiffness of annular ligaments measured in the superior trachea of human subjects and cadavers decreased gradually toward the distal trachea, whereas the mechanical stress relaxation time increased distally. There was no difference in dynamic stiffness between males and females in the upper part of the trachea; however, the dynamic stiffness of the middle and inferior parts was significantly higher in females than in males. Furthermore, males, but not females, showed significant differences in dynamic stiffness between the superior and middle parts. These results reveal that there are regional and sex-related differences in tracheal ligaments. This information might prove useful for surgical airway management and so on.