[The effect of the configuration of the thyroid cartilage on the asymmetry of the dorsal glottis and its significance for vocal function].

We investigated the effect of thyroid cartilage asymmetry on the posterior glottis. 1. Patients with vocal disorders showing "crossing" of the arytenoid cartilages underwent phoniatric and logopedic investigation as well as CT scan of the larynx in the horizontal plane. The shape of the thyroid cartilage and its relation to the other laryngeal structures were measured and analysed quantitatively. 2. Laryngeal serial sections in the horizontal plane were made and analysed in the same way. 3. Experiments were done in which the configuration of the thyroid cartilage was varied and the muscular influences were stimulated to produce typical anomalies of the posterior glottis. These investigations showed that there is a correlation between the configuration of the supraglottic thyroid cartilage and anomalies of the posterior glottis. Irregular growth of the thyroid cartilage causes different positions of the aryepiglottic folds with different positions of the corniculate cartilage during phonation. The shape of the anomaly described by us correlated in all cases with reduced vocal ability. It can now be assessed by CT.