Comparative anatomy of human and sheep laryngeal skeleton.

In a macroscopical study the dimensions of the adult laryngeal skeleton of man and sheep were compared. In both species the data for male and female were evaluated separately. In contrast to pronounced differences in size between male and female human larynges, the dimensions of both sexes in sheep proved to be very similar. In respect of 7 size values, the sheep larynx falls in the range between the male and female human larynx. This applies to most values for height, the antero-posterior diameter and the inferior breadth of the thyroid cartilage. In the sheep cricoid, the height of the lamina and the inner transverse diameter correspond closely to the human counterpart. The most conspicuous differences vis-à-vis the human larynx are the narrowing of the upper portion, the absent upper incisure of the thyroid and the relatively large dimensions of the arytenoid cartilages in sheep. Since in sheep the dimensions at the level of the glottis and of the subglottic space are within the range of the human larynx, the suitability of the sheep larynx as a model for experimental clinical laryngology is discussed.