23 o Epiglottis, fcfr. [Book IX, 



netted by a fhort, broad, and very ftrong ligament, 

 to the middle notch in the upper edge of that cartHage. 

 The- epiglottis is fome what concave behind and convex 

 before. Its fhape refembles that of the tongue, and 

 its termination or apex is always free, fo as by its own 

 elafticity to be naturally elevated. In deglutition, 

 however, when the tongue is drawn backwards, the 

 epiglottis is exa6tly applied over the rima glottidis, fo 

 as to prevent the food from paffing into the larynx, or, 

 as is commonly {aid, going the wrong way. 



The pharynx is every where connected by mufcular 

 fibres' to the larynx, and the larynx is in a manner fuf- 

 pendcd in its cavity. At the anterior part of the la- 

 rynx is placed a gland of confiderable fize, called the 

 thyroid gland. It is not difcovered to have any excre- 

 tory duct, and its ufe is unknown. 



The mufcles which regulate the motions of the glot- 

 tis, which is the principal organ of the voice, are the 

 following four pairs, and one fingle mufcle : 



The crico-arytenoideus poflicus arifes from the cri- 

 coid cartilage, and is inferted into the pofterior part of 

 thebafe of the arytenoid cartilage, By its contraction 

 it opens the rima glottidis a little, and by pulling back 

 the p.rytenoid cartilage, renders the ligament tenfe. 



The crico-rarytenoideus latcralis proceeds from the 

 cricoid cartilage laterally, \vhere it is covered by part 

 of the thyroid, and is inferted into the bait of the aryte- 

 noid cartilage. Its effect is to open the rima glottidis, 

 by feparating the arytenoid cartilage.-, and confequently 

 the ligaments which are fixed to them. 



The thyreo-arytenoideus arifes from the thyroid car- 

 tilage, runs backwards along the fide of the glottis, and 

 is inferted into the arytenoid cartilages. Its effect is 

 tu bring the thyroid and arytenoid carriages nearer to 



each 



