Function of the external laryngeal muscles in laryngeal adjustment (author's transl)

Abstract

The function of the external laryngeal muscles in laryngeal adjustment was experimentally investigated in the mongrel dog.Electrical stimulation was given to the nerve trunk innervating the pertinent muscle.oz muscle group.In someselected cases, sets of different muscle or muscle groups were simul-taneously stimulated.Positional changes in the laryngeal structures, especially of the laryngeal cartilages before and after stimulation were measured by means of double contrast roentgeno-graphy.Changes in the position and configuration of the vocal cord were observed by, simpl-taneous intralaryngeal photography.On the basis of the experimental data, biomechanical effects of the external laryngeal muscles on laryngeal adjustment were discussed.Through the present study, it was confirmed that the external laryngeal muscles imparted mechanical effects on the larynx basically in the following manner;1)the change in reciprocal positioning of the thyroid and cricoid cartilages, 2)the change in vertical position of the entire larynx, and 3)structural warp of the laryngeal frame-work.It was concluded that the change in the position and configuration of the vocal cord was induced by synergestic or antagonistic function of each external laryngeal muscle or muscle group, through the three basic pattern of the mechanisms mentioned above.