THE VOCAL FOLDS 



1223 



the ventricular appendix [appendix ventriculi laryngis] extends upward between 

 the ventricular fold medially and the thyreo-arytsenoid muscle and thyreoid car- 

 tilage laterally. Many mucous glands open into it. 



The appendix is occasionally so large as to reach the level of the upper margin of the thyreoid 

 cartilage or even the great cornu of the hyoid bone. The laryngeal pouches of some of the 

 apes are remarkably developed and appear to serve in affecting the resonance of the voice. 

 In man, their function, besides that of pouring out the secretion of the glands located within 

 their walls, is not known. 



The vocal fold [plica vocalis] (or true vocal cord) (figs. 970, 971, 987, 988) 

 is the thin edge of a full, lip-Hke projection, the vocal lip. The vocal folds cor- 

 respond in antero-posterior extent to the vocal ligament, and stand nearer the 

 median fine than the ventricular fold. In colour the vocal folds are pearly white, 

 excepting the anterior end of each, where there is a yellow spot [macula flava] 

 produced by a little mass of elastic tissue (sometimes cartilage) in the ligament. 

 The vocal lip [labium vocale] forms the floor of the ventricle and contains the upper 

 part of the elastic cone, whose thickened free edge, the vocal ligament, lies in the 



Fig. 988. — Frontal Section of a Larynx Hardened in Alcohol. 

 B. Anterior segment. (Poirier and Charpy.) 



Hyoid 



Cunei- 

 form 

 tubercle 



Ventri- 

 cular 

 muscle 



Appen- 

 dix 

 Thy- 

 reo- 

 arytae- 

 noid 

 (ext.) 



Cricoid 

 Crico- 

 t'ayreoid 



A. Posterior segment. 



Cricoid - 



B. 



Xrico- 

 thyreoid 



vocal fold and along the vocal muscle. The two vocal lips with the vocal folds 

 and the intervening space, the rima glottidis, together constitute the sound- 

 producing apparatus, the glottis. 



Below the vocal folds and the medial surfaces of the arytaenoid cartilages 

 is a slit, the rima glottidis (figs. 970, 971, 988), the narrowest part of the larj^ngeal 

 cavity, extending from the arytsenoideus transversus muscle posteriorly to the 

 thyreoid cartilage in front. The portion of the rima between the vocal folds is 

 known as the pars intermembranacea ; that between the arytsenoids the pars 

 intercartilaginea. The rima glottidis in easy respiration is narrow and has the 

 form of a long triangle; in laboured breathing it is widely open and lozenge-shaped. 



Below the level of the vocal folds is the space called the inferior entrance to 

 the glottis [aditus glottidis inferior] (fig. 988), which is narrow from side to side 

 above, wide and circular in section below — altogether somewhat funnel-shaped. 

 Its walls are formed by the elastic cone and by the arch and lamina of the cricoid 

 cartilage. The lining mucosa is separated from the elastic cone by numerous 

 glands and loose connective tissue, a condition favorable to the development of 

 oedema; below it is continuous with the mucosa of the trachea. 



By means of the laryngoscope a more or less complete picture of the laryngeal aperture 

 and the cavity of the larynx can be obtained (figs. 970, 971). There appear, highest up, the 



