Anatomical localization of the motor entry point in the thyroarytenoid muscle.

INTRODUCTION

The aim of this study was to localize the motor entry point (MEP) of the thyroarytenoid muscle.

METHODS

Eight cadaver larynges were dissected. A virtual plane was used to represent the MEP in a coordinate (X/Y/Z) system. The inferior border of the thyroid cartilage was linked to the center of the anterior arc of the cricoid cartilage (the Y-axis). The X-axis was set perpendicular to the Y-axis; the Z-axis passed through the posterior border of the thyroid lamina from the height of the insertion point.

RESULTS

The mean X, Y, and Z coordinates were 6.2 mm, 9.1 mm, and 11.0 mm, respectively. The calculated angles of the lateral and superior deflections were 29.4° and 35.8°, respectively. The calculated insertion depth, that is, the distance from the insertion point to the MEP, was 15.6 mm.

CONCLUSIONS

These results may help to improve the accuracy of needle insertion during diagnostic laryngeal electromyography or laryngeal electromyography-guided injections.