130 



ANATOMY FOR NUKSES. [CHAP. XII. 



where it blends with the trachea, but broad above, and shaped 

 somewhat like a triangular box, with flat sides and prominent 

 ridge in front. This prominence, popularly called "Adam's 

 apple," is formed by the union of the two largest pieces of 

 cartilage (the thyroid), of which the larynx is composed. 



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 or rima glottidis. 

 Imbedded in the mucous mem- 

 branes at the edges of the slit are 

 fibrous and elastic ligaments, which 

 strengthen the edges of the glottis 

 and give them elasticity. These 

 ligamentous bands, covered with 

 the mucous membrane, are firmly 

 attached at either end to the car- 

 tilages of the larynx, and are 

 called the vocal cords. The space 

 left between their edges, the glottis* 

 varies in shape and size, according 

 to the action of the muscles upon 



PHARYNX, WITH THE "COMMEND the laryngeal walls. When the 

 MENT OF GULLET AND LARYNX, AS larynx is at rest during quiet 



EXPOSED BY A SECTION A LITTLE TO , J , . , . . . 



THE LEFT OF THE MED^N PLANE OF breathing, the glottis is V-shaped; 

 THE HEAD, a, vertebrae ; 6, gullet ; during a deep inspiration, it be- 



c, trachea; d, larynx; e, epiglottis; , , ., , 



/, soft palate; g, opening of Eus- comes almost round; while, during 

 tachian tube; k, tongue; i, hard t he production of a high note, the 



palate; o, p, q, inferior turbinate 



bones of left nasal chamber. edges of the cords approximate so 



closely as to leave scarcely any 



opening at all. The glottis is protected by a 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 produce the voice. A blast of air, driven by 

 an expiratory movement out of the lungs, throws the two 



FIG. 88. THE MOUTH, NOSE, AND 



