CHAP. vii. J SPECIAL MUSCULAR MECHANISMS. 313 



thelium, the upper cells of which are flattened and devoid of cilia, 

 an epithelium in fact like that of the pharynx. In each vocal cord 

 the elastic fibres of the dermis undergo a large development, and 

 are arranged as a compact band running along the length of and 

 forming the chief part of the cord, the individual fibres and bundles 

 of fibres running on the whole horizontally, though not regularly 

 so, but interlacing in various planes ; each vocal cord is in fact a 

 cord of elastic tissue mixed up with some retiform tissue, wedge- 

 shaped in transverse section and covered with a layer of non-ciliated 

 epithelium. 



In the ventricles of the larynx, over the ventricular bands and 

 on the posterior surface of the epiglottis the mucous membrane 

 is rich in adenoid tissue which is often aggregated into distinct 

 follicles ; these parts are apt to become swollen or " cedematous " 

 ( 303) by the accumulation of fluid in the lymph spaces. Numerous 

 small glands, chiefly mucous but in part albuminous, are present 

 here and indeed over the larynx generally ; the vocal cords are 

 said to be destitute of them, but this is disputed. 



The thyroid and cricoid cartilages are formed wholly of hyaline 

 cartilage, and in old persons or even in middle life may be found 

 partially ossified. The arytenoid cartilage is also chiefly hyaline, 

 but parts of the surface and especially the processus vocalis are of 

 the yellow elastic variety. The cartilages of Santorini and Wris- 

 berg, as well as a small nodule of cartilage (cartilage of Luschka) 

 which is sometimes found imbedded in the front part of the vocal 

 cord, are all formed entirely of yellow elastic cartilage. 



904. If a small mirror, warmed in order to avoid the con- 

 densation of moisture upon it, be placed in an appropriate slanting 

 position, namely, at about an angle of 45 with the horizon, in the 

 back of the pharynx with its upper margin resting against the base 

 of the uvula and be adequately illuminated, a view of the interior of 

 the larynx may be obtained. Such a mirror with its various appur- 

 tenances is called a laryngoscope. The details of the view thus 

 gained will of course vary with the exact position and inclination 

 of the mirror, but the following may be taken as the average 

 appearance (Fig. 185). 



In front (reversed of course in the mirror image) will be seen 

 the edge of the back of the tongue (Z), and immediately in front 

 of this the top of the epiglottis (e.) These parts will of necessity 

 appear much fore-shortened, and peering out from underneath the 

 top edge of the epiglottis may be seen the swelling at its base 

 known as the " tubercle " or " cushion of the epiglottis " (e'). The 

 curved sides of the epiglottis will be seen sweeping away to the 

 right and to the left, and emerging from near the end of each 

 will be visible the ary-epiglottic fold (ar.ep.f.) on which are 

 obvious first the round swelling due to the cartilage of Wrisberg 

 (w} and next that due to the cartilage of Santorini (s). If at the 

 time when the view is being taken, the voice is being uttered and 



