THE LARYNX AND ARTICULATE SPEECH. 243 



the slit between them, called the glottis, is wide open. 

 This widening of the glottis is produced by two sets of mus- 

 cles called the crico-arytenoids (posterior and anterior) . 

 (The student will find much help in remembering the names 

 of these muscles if he keeps in mind that the name in every 

 case is derived from the two cartilages between which the 

 muscle exerts its pull.) The crico-arytenoid muscles are 

 muscles which are fastened at the outer basal corner of the 

 arytenoid, at the point marked P m in the diagram. From 

 this point one runs forward to be inserted on the inner side 

 of the cricoid, the anterior cricoid-arytenoid ; one backward 

 to be inserted on the back side of the cricoid, the posterior 

 crico-arytenoid. A moment's reflection will show that the 

 simultaneous contraction of these two muscles will tend to 

 pull the arytenoid cartilage to which they are attached out- 

 wards, and as this is true for both arytenoids, they will be 

 pulled apart, and as the vocal cords are attached to these 

 they will also be separated and the glottis opened. To make 

 this perfectly clear imagine a muscle attached at the point 

 P m , and inserted immediately below that at the base of the 

 cricoid. When that muscle contracts it is evident that the 

 arytenoid will be pulled out; that is, away from its fellow, 

 and so the glottis opened. 



2. The movements which bring the vocal cords into a 

 position to vibrate. In the production of vocal sounds the 

 glottis is very much narrowed. The vocal cords, and con- 

 sequently the arytenoids to which they are attached, are 

 moved towards each other. This approximation of the ary- 

 tenoids is brought about by two sets of muscles called 

 transverse and oblique arytenoids. The transverse aryten- 

 oids are bands of muscles which run from one arytenoid di- 

 rectly across to the other. The oblique arytenoids run from 

 the lower portion of one arytenoid to the upper portion of 

 the second arytenoid. It is quite obvious that by the con- 

 traction of these two sets of muscles, transverse and oblique, 

 the arytenoids will be pulled together, the vocal cords at- 

 tached to them brought closer together and the glottis nar- 



