Mechanism of the Larynx. 333 



Fig. 3 is a section of the Larynx similar to Fig. 2, but repre- 

 senting it as stripped of its mucous membrane, &c, leaving the 

 bare cartilages with the vocal ligament in its proper place, and 

 also the muscles. 



Fig. 4 is an external view of the corresponding half of the 

 Larynx, and Fig. 7 a bird's-eye view of the entire Larynx, both 

 in the same state of dissection. Fig. 8 is an enlarged sketch of 

 part of the upper half of Fig. 7. In these four figures the same 

 parts are indicated by the same letters. 



The cricoid cartilage is seen (Figs. 3, 4, ABC,) surmounting 

 the rings of the windpipe. The thyroid cartilage ECGH embraces 

 the cricoid, and is articulated to its sides by its lower horns at 

 C, so that it may be regarded as turning round the point C as 

 a fulcrum. As this discussion merely regards the motion of the 

 cartilages among themselves, it is of no consequence whether we 

 regard the cricoid or thyroid as fixed, and for convenience I shall 

 assume the cricoid as fixed for the present. 



Upon the upper surface of the back part of the cricoid are 

 seated two small cartilages (FF, Figs. 7, 8,) termed the arytenoids. 

 They are placed upon articulating surfaces which are formed on 

 the upper outer edge of the cricoid, and which may be considered 

 as portions of cylinders, whose axes are inclined, both with respect 

 to the horizontal and vertical sections. In the vertical section 

 the projection of this articulating axis is in the position BX, Fig. 3, 

 and in the horizontal in the line OP, Fig. 8. The base of each 

 arytenoid is spread out, and curved below Q, Fig. 8, so as to 

 lie upon this articulating surface, to which however it is so loosely 

 adapted as to permit a small degree of sliding motion transverse 

 to the axis. The arytenoids are however firmly tied to the back 

 of the cricoid by a bundle of strong ligaments BR BS, Fig. 8, 



U V 2 



