THE LARYNX. 



1819 



these and the sides of the epiglottis the fold contains only the general fibrous envel- 

 ope and some stray muscular hbres. Below the entrance in front lies the posterior 

 surface of the epiglottis, concave from side to side, and presenting in the median line, 

 from above downward, first a convexity, extending so far back as to overhang much 

 of the larynx, then a hollow, and finally a prominence, the tubercle or cushion. A 

 deep crease descends on each side, bounding the lower part of the epiglottis, and 

 meeting its fellow below the tubercle. The mucous membrane is very closely attached 

 to the epiglottis, and so thin that the straw color of the cartilage is seen through it, 

 turning into red at the lower part. The pits for the glands in its substance can also 

 be made out. The lateral wall of this region, which is separated from the front by 



Fig. 1545- 



Tongue 



Cushion of epiglottis 



Cuneiform tubercle. 

 Tubercle of Santorini 



Posterior crico-ar>tenoid 



muscle 



Cricoid cartilage 



Foramen caecum 



Right faucial tonsil 



Median ) ^, . , . , , . 



. \ Glosso-epiglottic fold 



Greater hyoid cornu 



Superior thyroid cornu 



Sinus pyriformis 

 Glottis 



Pharyngeal wall 



CEsophagus 



Pharynx opened from behind, showing superior laryngeal aperture and mucous pouches embraced by wings of 

 thyroid cartilage ; cricoid cartilage and muscles are covered with mucous membrane. 



the crease, inclines inward, and becomes the fold of mucous membrane known as the 

 false vocal cord. Farther back a shallow groove, \h^ philtrum, runs from the inter- 

 val between the tubercles of Santorini and of Wrisberg to the ventricle. 



The sinus pyriformis (Figs. 1545, 1354) is a shallow cavity to the outer side of 

 the aryepiglottic fold, bounded externally by the greater horn of the hyoid, the upper 

 part of the ala of the thyroid, and the thyro-hyoid membrane between them. It is 

 bilateral and properly a part of the pharynx (page 1598). Its mucous membrane, 

 continuous with that of the larynx, is smooth and thin, and but loosely attached to 

 the areolar tissue below it. In the front part there is a transverse fold caused by the 

 internal branch of the superior laryngeal nerve passing from the thyro-hyoid mem- 

 brane, which it perforates, to the larynx proper. 



