THE LARYNX AND ARTICULATE SPEECH. 245 



lage, d the band encircling the upper end of the trachea, / 

 and t parts of the thyroid cartilage, a the arytenoid carti- 

 lage, v c the vocal cords. Now, the crico-thyroid muscles 

 are attached atdfand inserted near /, and when they contract 

 they pull I down into the position of /'. But this stretches 

 the vocal cords, as the distance from a to t is shorter than 

 the distance from a to '. An apparent paradox appears 

 here. In the position f the vocal cords are actually 

 longer than in the position /, and yet in the longer position 

 are used to produce higher pitches. Other things being 

 equal, the longer string will produce a lower note, but the 

 slight increase in length here is much more than compen- 

 sated by an increase in the tension of it, and so the pitch 

 is raised. It is this crico-thyroid muscle which is most 

 commonly brought into play in the change of the pitch of 

 the voice. To bring the vocal cords, or rather to bring 

 the thyroid cartilage back into its natural position, there is 

 a muscle lying within each vocal cord and extending from 

 its insertion in the arytenoid to its insertion in the thyroid. 

 This muscle, the thyro-arytenoid is, therefore, the direct 

 antagonist of the crico-thyroid. 



Second, the pitch of the voice is also changed by short- 

 ening the vocal cords. This is accomplished by the crico- 

 arytenoid muscles already referred to in explaining the 

 widening of the glottis. When the anterior crico-arytenoids 

 contract it is evident that the arytenoids will be made to 

 rotate on their vertical axes in such a way that the point P m 

 is drawn inward and forward, but the point Pv to which the 

 vocal cords are attached drawn outwards and backwards. A 

 simultaneous contraction of the two anterior crico-arytenoids 

 would result in moving the inner points (Pv) together, and 

 if the contraction were strong enough, might put them in 

 contact. As the vocal cords are attached at the inner 

 points they will be brought into contact with each other and 

 so those portions of the vocal cords be prevented from vi- 

 brating. In other words, the vibrating portion of each 

 vocal cord is made shorter, and consequently the pitch is 



