[Characteristics of the motor innervation of the larynx]

Electromyography revealed the larynx crossed motor innervation in dogs. Unilateral transection of the inferior laryngeal nerve or its branches caused disappearance of electrical activity in the denervated inner laryngeal muscles as well as immobility of the vocal cord at the transection side and its paramedian transposition. Within 6 or more months after the transection, the periodic electrical activity occurring mainly in the abductor muscles in inhalation and in abductor ones in exhalation, was restored. The vocal cord remained in the same position. Transection of the inferior laryngeal nerve on the other side caused disappearance of the electrical activity not only in the laryngeal muscles innervated by this particular nerve but in analogous contralateral muscles where the nerve had been cut long ago, as well. Single electrical stimuli applied to the peripheral part of the cut inferior laryngeal nerve induced biphasic electrical responses in the inner laryngeal muscles on both sides. These findings suggest existence of the crossed motor innervation of the inner laryngeal muscles apart from their homolateral motor innervation.