VOICE AND SPEECH. 



be understood by help of the diagram, Fig. 184, in which t 

 represents the thyroid cartilage, c 

 the cricoid, a an arytenoid, and vc 

 a vocal cord. The muscle passes 

 obliquely backwards and upwards 



from about d near the front end of \ a } vc 



c, to t, about /, near the pivot (which 

 represents the joint between the 

 cricoid cartilage and the inferior 

 horn of the thyroid). When the 

 muscle contracts it pulls together 

 the anterior ends of t and c; either 

 by depressing the thyroid (as rep- 

 resented by the dotted lines) or by raising the front end of 

 the cricoid; and thus stretches the vocal cord, if the ary- 

 tenoid cartilages be held from slipping forwards. The an- 

 tagonist of the crico-thyroid is the tltyro-arytenoid muscle; 

 it lies, on each side, imbedded in the fold of elastic tissue 

 forming the vocal cord, and passes from the inside of the 

 angle of the thyroid cartilage in front, to the anterior angle 

 and front surface of the arytenoid behind. If the latter be 

 held firm, the muscle raises the thyroid cartilage from the 

 position into which the crico-thyroid pulls it down, and so 

 slackens the vocal cords. If the thyroid be held fixed by the 

 crico-thyroid muscle, the thyro-arytenoid will help to approxi- 

 mate the vocal cords, rotating inwards the vocal processes of 

 the arytenoids. 



The lengthening of the vocal cords when the thyroid 

 cartilage is depressed tends to lower their pitch; the in- 

 creased tension, however, more than compensates for this 

 and raises it. There seems, however, still another method 

 by which high notes are produced. Beginning at the bot- 

 tom of his register, a singer can go on up the scale some dis- 

 tance without a break; but, then, to reach his higher notes, 

 must pause, rearrange his larynx, and begin again. What 

 happens is that, at first, the^vocal processes are turned in, so 

 as to approximate but not to meet; the whole length of each 

 edge of the glottis then vibrates, and its tension is increased, 

 and the pitch of the note raised, by increasing contraction of 

 the crico-thyroid. At last this attains its limit and a new 

 method has to be adopted. The vocal processes are more 

 rolled in, until they touch. This produces a node (see 



