603 THE HUMAN BODY. 



thyro-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 ary- 

 tenoid 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 approximate 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 

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

 distance 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 at- 

 tains 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 Physics) at that point and shortens- 

 the length of vocal cord which vibrates. The shorter 

 string emits a higher note; so the crico-thyroid is relaxed, 

 and then again gradually tightened as the notes sung are 

 raised in pitch from the new starting-point. To pass- 

 easily and imperceptibly from one such arrangement of the 

 larynx to another is a great art in singing. There is some 

 reason to believe that a second node may, for still higher 

 notes, be produced at a more anterior point on the vocal 

 cords. 



The method of production of. falsetto notes is uncertain; 

 during their emission the free border of the vocal cords 

 alone vibrates. 



