332 Mr Willis on the 



from our view while living, for we cannot make much use of the 

 facts said to have been observed by some Physiologists in their 

 experiments on living animals, which are reported by men plainly 

 but loosely acquainted with Acoustics, and which, as they have 

 been deduced from a vocal mechanism vastly inferior to the hu- 

 man, may very probably mislead us if we attempt to apply them 

 to the explanation of the latter. 



Having now, in some degree, considered the uses of the Larynx, 

 and laid down some principles, we may proceed to examine its 

 structure with more minuteness. 



Upon removing the mucous membrane which lines the whole 

 of the interior of the laryngeal cavity, but leaving the vocal liga- 

 ments in their place, we find the latter supported in a curious 

 frame of cartilages united by certain ligaments and articulations, 

 and provided with muscles, by the action of which the cartilages 

 may be made to assume various positions with respect to each 

 other, and thereby alter the tension and relative position of the 

 vocal ligaments. 



The windpipe is found to consist of a pile of cartilaginous 

 rings, serving to keep the passage from the lungs always open, and 

 forming in this respect a contrast with the oesophagus, or tube 

 leading from the cavity of the pharynx to the stomach, which is 

 always closed by its muscular contractile structure, excepting at 

 the moment of the passage of food. In investigations concerning 

 the organs of voice the oesophagus may always be regarded as 

 having no existence. Its place is indicated in Fig. 2 by the 

 line IK. 



Above the rings of the windpipe, however, is a stout bony 

 annulus, denominated the cricoid cartilage, which serves as the 

 foundation of the mechanism we are about to describe. 



