Three-dimensional anatomic characterization of the canine laryngeal abductor and adductor musculature

The biomechanics of vocal fold abduction and adduction during phonation, re spiration, and airway protection are not completely understood. Specificall y, the rotational and translational forces on the arytenoid cartilages that result from intrinsic laryngeal muscle contraction have not been fully des cribed. Anatomic data on the lines of action and moment arms for the intrin sic laryngeal muscles are also lacking. This study was conducted to quantif y the 3-dimensional orientations and the relative cross-sectional areas of the intrinsic abductor and adductor musculature of the canine larynx. Eight canine larynges were used to evaluate the 3 muscles primarily responsible for vocal fold abduction and adduction: the posterior cricoarytenoid, the l ateral cricoarytenoid, and the interarytenoid muscles. Each muscle was expo sed and divided into discrete fiber bundles whose coordinate positions were digitized in 3-dimensional space. The mass, length, relative cross-section al area, and angle of orientation for each muscle bundle were obtained to a llow for the calculations of average lines of action and moment arms for ea ch muscle. This mapping of the canine laryngeal abductor and adductor muscu lature provides important anatomic data for use in laryngeal biomechanical modeling. These data may also be useful in surgical procedures such as aryt enoid adduction.