236 



ANATOMY FOR NURSES 



[Chap. XIIl 



by mucous membrane, which is continuous above with that lining 

 the pharynx, and below with that lining the trachea. 



The glottis. — Across the middle of the larynx is a transverse 

 partition, formed by two folds of the lining mucous membrane, 

 stretching from side to side, but not quite meeting in the middle 

 line. They thus leave in the middle line a chink, or slit, running 

 from front to back, called the glottis. The glottis is protected 

 by the leaf-shaped lid of fibro-cartilage, called the epiglottis, which 



shuts down upon the 

 opening during the 

 passage of food or 

 other matters into the 

 oesophagus. 



The vocal cords. — 

 Embedded in the mu- 

 cous membranes at the 

 edges of the slit are 

 fibrous and elastic lig- 

 a m e n t s , w li i c h 

 strengthen the edges 

 of the glottis and give 

 them elasticity. These 

 ligamentous bands, 

 covered with mucous 

 membrane, are firmly 

 attached at either end 

 to the cartilages of the 

 larynx, and are called 

 the true vocal cords, 

 because they function 

 in the production of the 

 voice. Al)ove the true 

 vocal cords are two 

 false vocal cords, so called because they do not function in the 

 production of the voice. 



Variations in size of glottis. — The glottis varies in shape and 

 size, according to the action of the muscles upon the laryngeal 

 walls. When the larynx is at rest during quiet breathing, the 

 glottis is V-shaped ; during a deep inspiration it becomes almost 



Fig. 142. — Tuk Larynx as seen by Means 



OF THE LaKYNUOSCOPE IN DIFFERENT CONDITIONS 



OF THE Glottis. A, while singing a high note ; B, 

 in fiuiot breathing ; C, during a deep inspiration. 

 I, ba.se of tongue ; e, upper free edge of epiglottis ; 

 e', cushion of the epiglottis ; ph, part of anterior 

 wall of pharynx ; cv, the true vocal folds ; cvs, the 

 false vocal folds ; ir, the trachea with its rings. 



