CROSS-INNERVATION OF THE THYROARYTENOID MUSCLE BY A BRANCH FROM THE EXTERNAL DIVISION OF THE SUPERIOR LARYNGEAL NERVE

The neuroanatomy of the larynx was explored in seven dogs to assess wh ether there is motor innervation to the thyroarytenoid (TA) muscle fro m the external division of the superior laryngeal nerve (ExSLN). In 3 animals, such innervation was identified. Electrical stimulation of mi croelectrodes applied to the ExSLN resulted in contraction of the TA m uscle, indicating that this nerve is motor in function. This was confi rmed by electromyographic recordings from the TA muscle. Videolaryngos troboscopy revealed improvement in vocal fold vibration following stim ulation of the ExSLN compared to without it. Previously, the TA muscle was thought to be innervated solely by the recurrent laryngeal nerve. This additional pathway from the ExSLN to the TA muscle may have impo rtant clinical implications in the treatment of neurologic laryngeal d isorders such as adductor spasmodic dysphonia.