405 



the sounds, and they take a veiled, and sometimes an extremely 

 muffled character ; an observation which we have already presented 

 to the reader's notice in speaking of the falsetto. 



Conjectures on the Formation of the different Registers. 



As the entire system of vibrations arises solely from the inferior 

 ligaments, it is evident that the cause of the different tones called 

 registers, must be sought for in the muscles which set these liga- 

 ments in motion ; and that the other parts of the larynx must be 

 considered only as apparatus for strengthening the sounds obtained, 

 and for modifying their quality. In our efforts to discover the more 

 intimate processes of the vocal organs which produce the sounds, 

 we shall recur at once to the observations already mentioned, to 

 some anatomical remarks which we are going to make, and to the 

 sensations which we feel in the organ itself whilst it is producing 

 sounds. 



If we detach one of the halves of the thyroid cartilage, we shall 

 see a large muscular surface of oblique fibres, which fills all the 

 space between the arytenoid and thyroid cartilages. At its upper 

 end is to be seen the muscle corresponding to the superior vocal 

 ligaments, and which sometimes extends to the notch in the 

 thyroid. After detaching this generally frail muscle, all the fibres 

 constituting this muscular surface seem to start from two opposite 

 centres, viz. the anterior surface of the arytenoid, and the re-enter- 

 ing angle of the thyroid. These centres, occupying the extremities 

 of a diagonal line, send their fibres towards each other in parallel 

 lines. Those which start from the anterior face of the arytenoid 

 descend obliquely ; the most external ones go to the cricoid, whose 

 posterior half they cover at the side ; the most internal ones de- 

 scend to the vocal membrane*, which they cover entirely. The 

 fibres which terminate at the membrane become longer, as they be- 

 come more internal. Those which start from the re-entering angle 

 of the thyroid, reascend obliquely to the summit of the arytenoid, 

 then diverge in order to form the sides of the ventricles, and then 

 disappear in the aryteno-epiglottidean folds and even the under sur- 

 face of the epiglottis. If we cut it away in successive layers, pro- 



* We thus designate that part of the membrane which goes from the bottom, 

 of the vocal ligament, to the edge of the cricoid. 



2 Q2 



