MUSCULAR ACTION 395 



out .this minute and careful control of the air-currents through the larynx 

 the significant functions of cultured and emotional speaking and singing 

 would be quite impossible. When one considers that the abdominal 

 muscles, the diaphragm, and many muscles of the thorax take part in 

 the respiratory movements, the wide-reaching extent in the body of the 

 influence of vocalization is obvious. 



THE LARYNX is the automatically adjusting reed-box by which the 

 voice is actually produced except apparently in one sort of whispering. 

 The essential organs of the larynx are the true vocal cords. The tonal 

 conditions of these vibrating reeds are determined and varied by the 

 nine intrinsic muscles of the larynx, not including those attached to the 

 epiglottis. In general terms there are four duties which these muscles 

 perform: to increase and decrease the effective vibratory length of the 

 vocal cords and the space between them. The former pair of functions 

 concern the pitch of the sound, the latter its loudness. 



THE AIR-CHAMBERS connected with the throat, nose, and mouth, 

 including the antrum of Highmore, are resonators of the tones started 

 in the larynx. Without these chambers the sounds produced by the 

 vocal cords would have little of that volume and richness in some degree 

 characteristic of all voices. It is largely owing to the uniqueness of the 

 combined shape of these chambers in each individual that each voice is 

 different from every other. 



The mouth-cavity, including the tongue and the lips, is, like the other 

 chambers above and in connection with the larynx, when closed a 

 resonance-chamber of the fundamentals and partials of the voice. It is, 

 however, much more than merely this, for only by means of its muscular 

 walls, so cleverly trained in the passing centuries, has spoken language 

 become possible. Speech is primarily a large and elaborate system of 

 vocal symbols, and these are produced almost wholly through the proper 

 adjustment and coordination of the muscles in and about the mouth- 

 cavity. Of these muscles, the tongue is by far the most versatile, 

 although the soft palate and the lips also play important parts in enun- 

 ciation. 



THE NERVOUS CONTROL of the mechanism of voice-production re- 

 quires little special mention, for the nerves actuating the separate parts 

 of the mechanism have been already discussed, while about the central 

 connections producing the complicated coordinations nothing in detail 

 is known. To the student of mental processes especially this neural 

 apparatus would have great importance could he know it, since it serves 

 better than any other in the body perhaps to link the events of idea- 

 formation with the motor events expressing them it "connects" more 

 closely than elsewhere, it may be, the body and the intellectual aspects 

 of the mind. We must think that the mental aspect of an idea is 

 somehow intimately associated with its symbols of motor expression to 

 others, but we do not know just where or even in what manner to look 

 to discover its material mechanism. Vocal movements, like other 

 gestures, involve muscles and the nerves which coordinate them, but the 



