TH?: LARYNX 905 



The internal is unimportant; it is tied to the corresponding cartilage and to the 

 cricoid by a til>ri)us l)and which is known as the transverse or crico-arytenoid 

 ligament. 



The borders. — The two internal, which limit the narrow inner face, are nearly 

 jKirallt-l and aliuust vertical; wliilst the external slojx's upwards, inwards, and 

 l)ackward<. 



The apex ])rojects inwards and backwards, and supports the corniculum. Tlie 

 cartilage here becomes tibrous in structure. 



The EPIGLOTTIS is a median leaf-like plate of yellow elastic cartilage attached 

 by a stalk infcriorly to the retiring angle of the thyroid cartilage below the median 

 notch. \\'hen denuded of its mucous covering, it is seen to be pitted with numerous 

 depressions for the lodgment of glands (fig. 580). 



Placed with its lingual surface al)ove, and its stalk in front, it has been 

 compared to an elongated saddle. It varies very considerably Vjoth in shape and 

 inclination, its leaf-like portion being sometimes considerably curled upon itself. 

 It is placed nearly vertically in the adult, but in children is frequently so much 

 depressed that its po.sterior free surface is inclined below its anterior. Hence its 

 varialde appearance when examined in the living subject with the laryngoscope. 

 It is somewhat depressed and folded upon itself during deglutition. 



Its anterior or lingual aspect is free aljove and covered with mucous membrane, 

 which lower down is reflected forward upon the base of the tongue in three folds — 

 one median (which encloses elastic tissue) and tAvo lateral — the glosso-epiglotti- 

 dean folds. Beneath the mucous membrane the deeper attached poi^^on of this 

 surfaci' is tied to the hyoid bone by a median elastic membrane, named hyo-epi- 

 glottidean ligament, and by small bands of muscular fibres. 



A ([uantity of elastic and fatty tissue, closely blended with the hyo-epiglotti- 

 dean ligament al)ove, connects the epiglottis to the thyro-hyoid membrane in front. 

 This is known as the periglottis (fig. 528). Still lower, the fibro-elastic tissue 

 which forms the thyro-epiglottidean ligament attaches the stalk to the thyroid car- 

 tilage. 



The posterior or laryngeal surface, concavo-convex from above downwards, and 

 concave from side to side, is free and covered with mucous membrane for its whole 

 exti-nt. Al)out its centre it projects backwards to form the cushion of the 

 epiglottis. 



Tlie lateral margins, which are free above, give attachment below to the aryteno- 

 epiglottidean folds of mvicous membrane which form the boundaries of the supe- 

 rior aperture of the larynx, and also on each side to a fold of the membrane, con- 

 taining fibrous tissue, which runs upwards to the posterior pillar of the fauces — 

 the pharyngo-epiglottidean fold. 



The CORNICULA LARYNGIS, or cartilages of Santorini, are the two little 

 cone-shaped yellow elastic cartilages which jiroject backwards and inwards from tlie 

 summits of the aryten(jids, with which they are sometimes directly continuous. 

 A joint, however, is usually present. 



The CUNEIFORM CARTILAGES, or cartilages of Wrisberg, are placed within 

 the aryteno-epiglottidean folds. Tiiese small conical and elongated yellow elastic 

 cartilages produce the thickenings of the folds in front of the cornicula. 



Calcification. — The hyaline cartilages of the larynx are especially ]irone to 

 calcify after middle life, but the yellow elastic cartilages take no share in the pro- 

 cess. The little cartilago triticea, however, which lies in the thyro-hyoid liga- 

 ment, is fre(|uently converted into bone. 



In the thyroid cartilage the deposit f)f l)ony salts usually commences near the 

 posterior V)order and in the cornua. extending forwards into the lower i>art of the 

 ala, and finally upwards, until in advanced cases the whole cartilage is involved. 



In the cricoid cartilage the calcification commences above on each side in the 

 neighbourhood of the crico-arytenoid joints, and extends downwards, and finally 

 both forwards and backwards. 



In the arytenoid the calcification commences in the ba.se, but it finally involves 

 the whole cartilage with the exception of the sunnint, where the hyaline structure 

 (as already noted) disa)i)x>ars. 



The ligaments (extrinsic). — The thyro-hyoid membrane is composed 



