Mechanism of the Larynx. 341 



With respect to the scale of notes in the human voice, which is 

 termed the falsetto, I shall merely observe that it is at present ex- 

 tremely doubtful whether it owes its peculiar quality to some change 

 in the laryngeal mechanism, or in the superior cavity ; the motion 

 of the cartilages observed by the finger from without shews that 

 the tension and consequent diminution of the aperture ED, Fig. 2, 

 goes on in the production of these notes just as it does in that of 

 the natural tones, and is therefore carried so far in the higher notes 

 of the falsetto that the space ED is completely obliterated by the 

 upper edge of the cricoid touching the lower border of the thyroid. 



According to M. Magendie* the vocal ligaments of a dog 

 vibrate through their whole length while producing deep notes, 

 but in high notes the hinder portion only vibrates, the thyroidean 

 extremities being closed together so as to shorten the aperture of 

 the glottis, this diminution of the glottis becoming greater and 

 greater as the notes rise in pitch. Should this ever be established 

 to be the case in man, I should not be surprised if it were found 

 that only during the production of the natural scale the vocal liga- 

 ments vibrate through their whole length, after the manner I have 

 described already ; while for the production of the falsetto notes 

 the following changes may be introduced. If the arytenoids be 

 pressed together by the aryteno'idei transversi and cricoaryteno'idei 

 laterales, and at the same time lifted up into the vocal position 

 by the thyieoarytenoi'deif, the complete closing of the passage 

 will be prevented, and notes will be produced by the action of 



» T. I. p. 215. 



t The cricoaryteno'idei laterales press the points /' together (Fig. S), at the same time 

 depressing them ; but the thyroarytenoid^ approximate the points V, at the same time raising 

 them, and without bringing them into contact. If both these muscles act at once the raising 

 effect of the latter is greater than the depressing effect of the former, because the latter acts 



x x 2 



