488 



MOVEMENTS-VOICE AND SPEECH. 



of the acts of walking, running, leaping, swimming etc. ; but it has been 

 thought better to omit these subjects, rather than to enter so minutely as 



would be necessary into anatomical details 

 and to give elaborate descriptions of move- 

 ments that are simple and familiar. 



VOICE AXD SPEECH. 



The principal organ concerned in the pro- 

 duction of the voice is the larynx. The ac- 

 cessory organs are the lungs, trachea, expi- 

 ratory muscles, the mouth and the resonant 

 cavities about the face. The lungs furnish 

 the air by which the vocal chords are thrown 

 into vibration, and the mechanism of this 

 action is merely a modification of expiration. 

 By the action of the expiratory muscles the 

 intensity of vocal sounds is regulated. The 

 trachea not only conducts the air to the 

 larynx, but it may assist, by resonance, in 

 modifying the quality of the voice. Most 

 of the variations in the tone and quality, 

 however, are effected by the action of the 

 larynx itself and of the parts situated above 

 the larynx. 



Sketch of the Physiological Anatomy of 

 the Vocal Organs. The vocal chords are 

 stretched across the superior opening of the 

 larynx from before backward. They consist 

 of two pairs. The superior, called the false 

 vocal chords or the ventricular bands, are not 

 concerned in the production of the voice. 

 They are less prominent than the inferior 

 chords, although they have nearly the same 

 direction. They are covered by a thin mu- 



19 



FIG. 166. Longitudinal section of the 



human larynx, showing the vocal 



chords (Sappey). 

 1, ventricle of the larynx ; 2, superior 



vocal chord; 3, inferior vocal chord ; 



4, arytenoid cartilage ; 5, section of 



the arytenoid muscle ; 6, 6, inferior 



portion of the cavity of the larynx ; 



7, section of the posterior portion of 



the cricoid cartilage ; 8, section of 



the anterior portion of the cricoid 



cartilage : 9. superior border of the 



cricoid cartilage ; 10, section of the 



thyroid cartilage : 11. 11, superior 



portion of the cavity of the larynx ; 



12. 13. arytenoid gland ; 14, 16, epi- 

 glottis : 15. 17, adipose tissue : 18, 



section of the hyoid bone ; 19, 19, 20, 



trachea. . . 



cous membrane, which is closely adherent to 



the subjacent tissue. The chords themselves are composed of ordinary 

 fibrous tissue, with a few elastic fibres. 



The true vocal chords, or vocal bands, are situated just below the superior 

 chords. Their anterior attachments are near together, at the middle of the 

 thyroid cartilage, and are immovable. Posteriorly they are attached to the 

 movable arytenoid cartilages ; and by the action of certain muscles, their 

 tension may be modified and the chink of the glottis may be opened or closed. 

 These are much larger than the false vocal chords, and they contain a great 

 number of elastic fibres. Like the superior vocal chords, they are covered 

 with a very thin and closely adherent mucous membrane. The mucous 

 membrane over the borders of the chords is covered with flattened epithelium 



