PLATE LII. 

 THE LARYNX. NATURAL SIZE. 



In this plate are represented three dissections of the larynx. Fig. I. shows a 

 jiostcrior view with the mucous membrane removed, to show the nerves aud muscles ; 

 Fig. II. a side view, with the posterior part of the right side of the thyroid removed ; and 

 Fig. III. a deeper view of the same, to show the deep portion of the thyro-ary tenoid muscle 

 and its connection with the true vocal cords. 



Morphology of the Vocal Cords. 1 Mr. Sutton has pointed out that the false vocal 

 cords of man are connected in front with the innor surface of the thyroid cartilage, and 

 also the base of the epiglottis ; embedded in their Substance are the cuneiform cartilages, 

 and on tracing the false cords backwards to their attachment to the arytenoids, accessory 

 slips will be found connecting them with the coruicula laryngis. In the porpoise there 

 is an azygous epiglottis and an enormously prolonged cornicula laryngis which, though 

 separate, are bound together by dense fibrous tissue. From the base of the epiglottis 

 a process of cartilage projects which is joined by fibrous tissue with a style-like process 

 of cartilage projecting from the cornicula laryngis ; and in this fibrous tissue are 

 nodules of cartilage. In the ant-eater there is a well-developed epiglottis, and directly 

 continuous with its body is a process of cartilage which, passing backwards, becomes 

 continuous with that overtopping the arytenoids ; this body causes a projection in the 

 mucous membrane and forms the false vocal cord. In the horse there is a thick bar of 

 cartilage continuous with the base of the epiglottis projecting backwards into the false 

 vocal cords. 



Thus, in man the false vocal cords with the cuneiform cartilages are the degenerate 

 representatives of the piece of cartilage by means of which the cornicula laryngis and 

 the epiglottis were originally united, and, with the cornicula, must be regarded as vestigial 

 structures. 



The True, Cords may be considered as the tendinous part of the thyro-arytenoid 

 muscle, which is intimately connected with it. 



The Hyo-epiglottic Ligament. In the horse a muscle replaces this ligament, which 

 has occasionally even in man been seen to be muscular. It attains its greatest 

 development in those animals with an intra-narial epiglottis. 



1 Eland Sutton, Journal of Anat. and Phys. vol. xiiii. p. 256. 



