544 



VOICE AND SPEECH 



vary in length in men from 15-20 mm. (average 18.22 mm.) and in 

 women from 10-15 mm. (average 12.6 mm.). Their free edges are 

 thin and tilted slightly upward, while their outer margins are straight 

 and are everywhere adherent to the wall of the larynx. The yellow 

 elastic fibers composing their substance, are closely interwoven and 

 pursue in general a longitudinal course. Of functional importance is 

 also the fact that these bands are covered with thin, flat, stratified 

 epithelium, while the remaining extent of the larynx is lined with colum- 

 nar, ciliated epithelium. The effective stroke of these cilia is executed 

 toward the pharynx, i.e., in the same direction as that of the cilia 

 found in the trachea and bronchi. 



The space above the vocal cords is known as the supraglottic 

 cavity. It is bounded above by the epiglottis". On each side of the 



2 



FIG. 269. THE LARTNGOSCOPIC IMAGE IN EASY BREATHING. (Stoerk.) 

 1, Base of the tongue; 2, median glosso-epiglottic ligament; 3, vallecula; 4, lateral 

 glosso-epiglottic ligament; 5, epiglottis; 6, cushion of epiglottis; 7, cornu major of hyoid 

 bone; 8, ventricular band, or false vocal cord; 9, true vocal cord; opening of the ventricle 

 of Morgagni seen between 8 and 9; 10, folds of mucous membrane; 11, sinus pyriformis; 

 12, cartilage of Wrisberg; 13, aryteno-epiglottic fold; 14, rima glottidis; 15, arytenoid 

 cartilage; 16, cartilage of Santorini; 17, posterior wall of pharynx. (American Text- 

 book of Physiology.) 



latter a fold of mucous membrane extends obliquely downward and 

 backward, forming the lateral boundary of the aperture of the larynx, 

 and covering the arytenoid cartilages. Besides these aryepiglottic 

 folds, the mucosa of the larynx also presents two transverse ridges, 

 one on each side, which are known as the false vocal cords. These 

 relatively narrow bands are situated a short distance above the true 

 vocal cords and are placed practically parallel to these, so that a long 

 slit-like space is left between them. The function of these bands is not 

 fully understood, but it has been assumed that they serve to protect 

 the true vocal cords against injury and excessive vibration. In the 

 second place, it is held that they serve as sphincters of the larynx, 

 their approximation tending to render the corresponding movement 



