M. Savart on the Mechanism of the Human Voice. 207 



gives to the bottom and the external side of the ventricle, as 

 well as to the margin of the orifice by which the air escapes 

 from the trachea, the degree of tension necessary for the sound 

 which it is wished to produce. By the extremities of its ob- 

 lique fibres, it acts also upon the fold of the mucous mem- 

 brane which forms the upper part of the extensible portion 

 of the vocal tube. Its action upon this part is supported by 

 that of a small muscle, which ought to be called the superior 

 thyro-arytenoidian, for it stretches obliquely from below up- 

 wards, from behind to before the external and inferior part of 

 the arytenoid, to the upper part of the rounded angle of the 

 thyroid, where it is fixed by very short tendinous fibres. This 

 is a small conical muscular bundle whose base is behind. It 

 is always more developed on one side of the body than on 

 the other. Several oblique fibres of the thyro-arytenoidian 

 are confounded with that small muscle, into which they are 

 inserted almost perpendicularly. Others go beyond this into 

 the mucous fold. It is obvious, that the use of this muscu- 

 lar bundle is to stretch the external sides of the ventricle con- 

 jointly with the oblique fibres of the thyro-arytenoidian, to 

 which they serve as a point of support. 



The superior ligaments CC have no proper muscle, but 

 they are formed of a substance sufficiently rigid, and they are 

 thick enough not to require any foreign support. Though 

 their free margin is rounded, yet this cannot at all injure the 

 production of sounds, as we have already noticed. 



One of the most remarkable arrangements of the vocal ap- 

 paratus of man is, that the larynx is terminated above by two 

 folds of the mucous membrane, which float in the middle of 

 the air which sounds around them, and of whose motion they 

 necessarily partake. It cannot be doubted that these folds 

 ought to have a great influence on the faculty of modulating 

 and articulating sounds, as well as upon the timbre of the 

 voice ; for the inferior larynx of all birds that have a varied 

 song, or which are capable of learning to speak, present an 

 analogous arrangement, whilst in birds whose voice is limited, 

 nothing like this is to be found, even when their larynx is 

 provided with the proper muscles. These floating membranes, 

 being susceptible of a variable tension, ought to be principal- 



