224 



ELEMENTARY PHYSIOLOGY 



lage. Its use is to close the upper opening of the larynx (the 

 space between the vocal cords) during the act of swallowing, thus 



Fig. 216. Posterior Muscles of the 

 Larynx. 



i, posterior crico-arytenoid ; 2, arytenoid ; 

 3, 4, oblique fibres passing round the edge 

 of the arytenoid cartilages to form 5, the 

 muscles which connect these cartilages with 

 the epiglottis. 



preventing particles of food or 

 drink from passing into the trachea. 

 During quiet breathing the 

 vocal cords are relaxed, the glottis 

 Is wide, and the air passes through 

 freely. When we wish to speak 

 or sing, we cause certain muscles 

 to stretch the cords and bring 

 them near each other. Under 

 these conditions the out-rushing 

 air sets them in vibration, thus 

 producing sound. 



Fig. 217. Three Views of the 

 Larynx during Life, as seen 

 by looking down the throat 

 with the aid of the Laryngo- 

 scope. A, during the sing- 

 ing of a high note ; B, 

 during quiet breathing ; 

 C, while taking a very deep 

 breath. 



/, base of the tongue ; e, upper free 

 part of the epiglottis ; e', lower por- 

 tion of the epiglottis ; ph, front wall 

 of the pharynx behind the larynx ; 

 a., tip of the arytenoid cartilage ; 

 cv, vocal cords ; cvs, superior or false 

 vocal cords, which do not aid in the 

 production of the voice; tr, front 

 wall of the trachea ; b, commence- 

 ment of the two bronchi. 



The contraction of muscles connecting the thyroid with the arytenoid 

 cartilages (the thyro-arytenoid muscles) causes them to approach each other, 



