CHAPTER XXIII. 

 PHONATION; ARTICULATE SPEECH. 



Phonation, the emission of vocal sounds, is accomplished by the 

 vibration of two elastic membranes which cross the lumen of the 

 larynx antero-posteriorly and which are thrown into vibration by a 

 blast of air from the lungs. 



Articulate speech is a modification of the voice produced by the 

 teeth and the muscles of the lips and tongue and employed for the 

 expression of ideas. 



The larynx, the organ of the voice, is situated in the forepart of 

 the neck, occupying the space between the hyoid bone and the upper 

 extremity of the trachea. In this situation it communicates with the 

 cavity of the pharynx above and the cavity of the trachea below. 

 From its anatomic relations and its internal structure the interpola- 

 tion of the elastic membranes the larynx subserves the two widely 

 different yet related functions, respiration and phonation. 



THE ANATOMY OF THE LARYNX. 



The larynx consists primarily of a series of cartilages united one 

 with another in such a manner as to form a more or less rigid frame- 

 work, yet possessing at its different joints, a certain amount of 

 motion; and, secondarily, of muscles and nerves which conjointly 

 impart to the cartilages the degree of movement necessary to the 

 performance of the laryngeal functions. It is covered externally 

 by fibrous tissue and lined throughout by mucous membrane con- 

 tinuous with that lining the pharynx and trachea. 



The larynx presents a superior or pharyngeal and an inferior or 

 tracheal opening. The pharyngeal opening is triangular in shape, 

 the base being directed forward, the apex backward. The plane of 

 this opening in the living subject is almost vertical. The tracheal 

 opening is circular in shape and corresponds in size with the upper 

 ring of the trachea. Viewed from above, the general cavity of the 

 larynx is seen to be partially subdivided by two membranous bands 

 the vocal bands or cords which run from before backward in a hori- 

 zontal plane. The space between the bands, the glottis, varies in 

 size and shape from moment to moment in accordance with respira- 

 tory and phonatory necessities. The average width of the glottis, at 



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