Action Potentials from Internal Laryngeal Muscles during Phonation

Abstract

ELECTROMYOGRAPHY of the internal laryngeal muscles has been applied in the diagnosis of laryngeal palsy by Weddell, Feinstein and Pattle¹. In a study of phonation, Katsuki² recorded action potentials from the m.crico-thyreoideus externus in a case with partial resection of the larynx. In the present study, action potentials were recorded by means of concentric needle electrodes inserted in the m.thyreo-arytaenoideus internus (m.vocalis), crico-thyreoideus externus, inter-arytaenoideus transversus and crico-arytaenoideus posterior (m.posticus) of normal subjects and of patients with laryngeal paresis. In addition, the action potential amplitude was averaged electrically and recorded as an expression of the degree of activity. The subject spoke into a condenser microphone, the output of which was amplified and recorded simultaneously with the action potentials.