1068 



THE KESPIKATOEY SYSTEM. 



elevations of mucous membrane which proceed from the lateral margins of the 

 epiglottis to the lateral walls of the pharynx at the side of the tongue. Between 

 the two layers of mucous membrane which form each of these folds is a certain 

 amount of elastic tissue. By the three folds the depression between the root 

 of the tongue and the epiglottis is marked off into two fossae, termed the epiglottic 

 valleculae. From the lateral margins of the epiglottis there also pass off the 

 plicae aryepiglotticae to the arytaenoids. 



The ligamentum hyoepiglotticum is a short, broad elastic band, somewhat 

 broken up by adipose tissue, which connects the ventral surface of the epiglottic 

 cartilage to the upper border of the hyoid bone (Fig. 853, p. 1073). The liga- 

 mentum thyreoepiglotticum is strong and thick (Fig. 855, p. 1075). Composed 

 mainly of elastic tissue, it proceeds downwards, from the inferior pointed extremity 

 of the epiglottic cartilage, and is attached to the angular depression between the 

 two laminae of the thyreoid cartilage, below the median notch. 



A triangular interval is left between the ventral surface of the epiglottis and 

 the hyo-thyreoid membrane. This is imperfectly closed above by the hyo- 

 epiglottic ligament, and contains a pad of soft fat (Fig. 851, p. 1070). 



CAVUM LARYNGIS. 



The cavity of the larynx is smaller than might be expected from an inspection 

 of its exterior. On looking into its interior, through the laryngeal aperture, it is 

 seen to be subdivided into three portions by two pairs of elevated folds of mucous 

 membrane, which extend ventro-dorsally (antero-posteriorly), and project medially 

 from each lateral wall of the cavity. The upper pair of folds are the ventricular 

 folds (O.T. false vocal cords) ; the lower, more definite pair, are the vocal folds (O.T. 



true vocal cords) (Fig. 849). 

 The latter are the chief 

 agents in the production 

 of the voice, and the 

 larynx is so constructed 

 that changes in their 



Pharyngo- 

 epiglottic 



ligament 

 -Epiglottis 



Pharyngeal 



surface of 



tongue 



Hyoid bone 



Glosso- 



epiglottic 



ligament 



Vocal fold 



Epiglottic, yjillecula 



relative position and in 

 their degree of tension 

 are brought about by the 

 -Tubercieofepigiottis action of the muscles and 

 the recoil of the elastic 

 ligaments. 



Aditus Laryngis. - 

 The laryngeal aperture is 

 a large obliquely placed 

 opening, which slopes 

 rapidly in a dorsal and 

 downwards direction and 

 looks upwards and dorsally 

 into the laryngeal part of 

 the pharynx. Somewhat 

 triangular in outline, the 

 basal part of the aperture, 

 placed superiorly and 

 vent rally, is formed by the 

 free border of the epiglottis. The opening rapidly narrows as it runs downwards, 

 and it ends in the interval between the two arytsenoid cartilages. The sides oi 

 the aperture are formed by two sharp and prominent folds of mucous membrane 

 called the ary-epiglottic folds, which stretch between the lateral margins of the 

 epiglottis, ventrally, and the arytaenoid cartilages dorsally. The two layers o: 

 mucous membrane which compose the ary-epiglottic folds, enclose, between them 

 some connective tissue, muscular fibres belonging to the ary-epiglottic muscles, anc 

 in their dorsal parts the cuneiform and corniculate cartilages, which latter surmoun 1 



Ary-epiglottic 



fold 



Laryngeal ventricle 



.Ventricular fold 

 Cuneiform tubercle 



Corniculate 

 tubercle 



Posterior aspect of 

 cricoid cartilage 



Pharyngeal 

 wall (cut) 



FIG. 849. ADITDS LARYNGIS, EXPOSED BY THE REMOVAL OF THE 

 DORSAL WALL OF THE PHARYNX. 



