Abstract
Differences in the rotation and tilt of normal human larynges were investigated in 61 adult subjects of different ages and sexes utilizing computed tomography. The subjects were divided into two age groups: a young group aged from 20 to 30 years old (YG) and old group aged from 50 to 70 years old (OG). All subfects were right handed. The results are summarized as follows:
1. The laryngeal framework, namely the thyroid cartilage (TC), was observed to be rotated to the right toward an anteroposterior axis of the vertebrae, particularly in the OG males. However, the degree of rotation of the cricoid cartilage (CG) to-ward the same axis was smaller than that of the TC in both groups of males and in the YG of females.
2. Regarding the tilt of the larynx, no remarkable difference was demonstrated with regard to age or sex.
3. In the laryngeal framework, the TC rotated to the right toward an anteroposterior axis of the CC in the OG males. It therefore appears that the main factor effecting rotation between the TC and CG is age in males.
