Section 2. 



T he Larynx. 



The larynx serves a twofold purpose — viz., respiration and 

 phonation ; in animals the former holds the more important 

 position, the voice-producing function being of a very subordinate ^- 

 character. 



The larynx may be described as a cartilaginous box placed 

 at the summit of the trachea, the opening into it being capable 

 of increasing or de- 

 creasing in size, and so 

 allowing a larger or 

 smaller amount of air 

 to enter the lungs. 

 Within the larynx are 

 two elastic cords ar- 

 ranged V-shaped, the 

 function of which is 

 connected solely with 

 the production of sound 

 (Fig. 54. 3). Both the 

 respiratory and vocal 

 functions require that 

 the several parts of the 

 larynx should move — 

 viz., that the mouth of 

 the organ should be 

 widened or narrowed, 

 or that the cords should 

 be approximated, 

 drawn apart, tightened, 

 or slackened. These 

 movements are brought 

 about by certain groups 

 of muscles, those which 

 approximate the walls 

 of the glottis being 

 known as the adduc- 

 tors, whilst those which widen it are known as the abductors. 



The Muscles of the Larynx may therefore be divided into 

 those of respiration and phonation. As the most important 

 feature in respiration is the opening or dilating of the glottis, 



US 10 



Fig. 54. — The Laryngeal Opening during 

 Ordinary Respiration. 



1, The epiglottis ; 2, margin of arytenoids ; 3, 

 vocal cord ; 4, pharynx laid open. The 

 V-shaped slit is the glottis. Note how 

 much wider the epiglottis is than the open- 

 ing it has to cover. 



