1224 THE RESPIRATORY SYSTEM 



root of the tongue with the epiglottic valleculse and glosso-epiglottic folds leading backward 

 to the epiglottis; behind the latter, the triangular aperture of the larynx, bounded at the sides 

 by the ary-epiglottic folds. Further laterahvard appear the piriform recesses, the laryngeal 

 portions of which lie as transverse fissures behind the laryngeal aperture. Within the ary- 

 epiglottic folds are seen the prominent corniculate tubercles on either side of the inter- 

 arytsenoid commissure and just anterior, the variable cuneiform tubercles. Within the vesti- 

 bule the epiglottic tubercle rises upon the anterior wall, while at the sides appear the ventricular 

 folds overhanging the slit-hke openings of the laryngeal ventricles. Below this level the vocal 

 folds stand out on either side approaching nearer the median plane than do the ventricular 

 folds and conspicuous by their pearly whiteness. The form and extent of the rima glottidis 

 and of its divisions, the intermembranous and intercartilaginous parts, can be inspected. Far 

 down, the cricoid cartilage and anterior wall of the trachea may appear and under favourable 

 conditions a glimpse of the bifurcation of the latter can be obtained. 



The mucous coat of the larynx [tunica mucosa laryngis] in general is covered by a ciliated 

 epithelium; the vocal lips, and, exceptionally, small areas of the mucosa of the laryngeal surface 

 of the epiglottis and the ventricular folds possess a covering of flat, non-ciliated cells. The 

 attachment of the mucosa to the underlying parts is very firm about the vocal folds and dorsal 

 side of the epiglottis, and loose in the ary-epiglottic folds, where much areolar tissue is present. 

 In general the mucosa is pink in colour, becoming bright red over the epiglottic tubercle and 

 edges of the epiglottis and fading over the vocal folds, which appear almost white. 



Numerous mucous glands [glandula; laryngea;] occur about the larynx and are aggregated 

 into groups in certain places. One cluster of anterior glands [gl. laryngeal anteriores] is found 

 in front of and on the posterior side of the epiglottis; another, the middle glands [gl. laryngeae 

 mediae], is in the ventricular fold, in the triangular fovea of the arytsenoid cartilage and clustered 

 about the cuneiform cartilage, while a third set, the posterior glands [gl. laryngese posteriores], 

 is disposed about the transverse arytsenoid muscle. Many glands pour their secretion into the 

 appendix of the laryngeal ventricle, but there are none on or about the vocal folds. Lymph- 

 nodules of the larynx [noduli lymphatici laryngei] occur in the mucosa of the ventricle and on 

 the posterior surface of the epiglottis. 



Position and relations. — The larynx opens above into the pharynx by the aditu and in thiss 

 region is connected with the hyoid bone. Below, its cavity leads into the trachea. Its position 

 in the neck is indicated on the surface by the laryngeal prominence (Adam's apple). It stands 

 in front of the fourth, fifth, sixth, and seventh cervical vertebras; from these it is separated by 

 the prevertebral muscles and the pharynx, into the anterior wall of which it enters. The 

 integument and cervical fascia cover the larynx anteriorly in the middle line, while toward the 

 side are the sterno-hyoid, sterno-thryeoid, and thyreo-hyoid muscles. The lateral lobe of the 

 thyreoid gland and the inferior constrictor of the pharynx are in relation to it laterally, while 

 further removed are the great vessels and nerves of the neck. 



Peculiarities of age and sex. Position. — The larynx is placed high in the neck in foetal 

 and infantile life and descends in later life. In a six-months foetus the organ is two vertebrae 

 higher than in the adult. (Symington.) The descent of the larynx has been attributed to 

 the vertical growth of the facial part of the skull, but this cause is questioned by Cunningham, 

 who points out the high position of the larynx in the anthropoid apes, where the facial growth 

 is more striking than in man; it appears also that the larynx follows the thoracic viscera in their 

 subsidence, which, according to Mehnert, continues until old age. At birth the interval between 

 the hyoid bone and thyreoid cartilage is relatively very small and increases but little during 

 early life. 



Growth and form. — The larynx of the new-born is relatively large and in contour more 

 roimded than that of the adult. The organ continues to grow imtil the third year, when a 

 resting period begins, lasting until about twelve years of age, during which time there appears 

 to be no difference between the larynx of the male and that of the female. At puberty, while 

 no marked change is observable in the larynx of the female, rapid growth accompanied by 

 modification of form of the larynx is initiated in the male. The laryngeal cavity is enlarged, 

 the antero-posterior diameter markedly increased; the whole framework becomes stronger; the 

 thyre(nd cartilage especially increases greatly in its dimensions, giving rise to the laryngeal 

 prominence; the vocal folds are lengthened and thickened, the voice changing in quality and 

 pitch. These changes are, for the most part, effected in about two years, but complete develop- 

 ment is not attained before twenty to twenty-five years of age. Castration is known to in- 

 fluence the development of the larynx, for in the eunuch it has been found to resemble that of a 

 young woman. The changes in the structure of the cartilages have already been described. 



Dimensions.^-In the male the distance from the upper edge of the epiglottis to the lower 

 margin of tlu; cricoid is 70 mm.; in the female, 48 mm. The transverse diameter is 40 mm. 

 in the male, .io mm. in tlie fenuile. The greatest sagittal diameter is 40 mm. in the male, 37 

 mm. in the female. The vocal folds in the male measure relaxed about 15 mm., in the fenuile, 

 but 11 mm.; when stretched, about 20 nun. and If) mm. respectively. 



The length of the rima glottidis in the quiescent state is on the average 23 mm. in the male; 

 17 mm. in the; female. In the male the jiars intermembranacea measures 15.5 mm., the pars 

 intercartilagin(!a, 7.5 mm. In the female these arc 11.5 mm. and 5.5 mm. respectively. The 

 rima may be lengthened by stretching of the vocal folds to 27.5 mm. in the male and 20 mm. in 

 the female. (Moura.) In the male the width of the rima glottidis is 0-8 mm. in its widest 

 part, but may be increased nearly to 12 mm. 



Vessels and nerves (figs. '.)8b, 985). — The arU'rics supplying the larynx are the superior 

 anfl inferior laiyngcul, wliicli afcompany the internal and inferior laryngeal nerves respectively, 

 and the crico-tliyreoid arteries (see pp. 538, 501). 



The .superior and inferior laryngeal yeiAt.s join tius superior and inferior tiiyreoid veins re- 

 spectively. 



The lymph vascular system is well developed throughout the larynx generally, but in the 



