Till: LA It Y XX. 4.V, 



function is particularly marked in phonation, when it modifies the length, 

 separation, ainl tension of tlie vocal cords. 



AUYTENOIDEUS. Situated beneath the pharyngcal mucous membrane, 

 above the arytenoid cartilages, this, the smallest of the laryngeal muscles, is 

 composed of two lateral portions whose fibres arise from a median rapho 

 and, diverging, pass to the superior part of the external face of the befon- 

 nu'iitioned cartilages, where they terminate by becoming inserted into the 

 crest dividing that face, and uniting with the thyro-arytcnoid muscle. 



The French works on Veterinary Anatomy cite this muscle wo do not 

 know why as a dilator of the larynx. Its position in front of the crico- 

 arytenoid cartilages sufficiently indicates that it cannot act otherwise than 

 in bringing the two arytenoid cartilages together. And the continuity of 

 a large number of its fibres with those of the thyro-arytenoideus, does not 

 allow it to have any other action than that of this muscle. 



3. Mucous membrane of tltc larynx. This membrane is only a con- 

 tinuation of the pharyngcal mucous membrane, which, after covering the 

 prominence formed by the opening of the larynx, is folded over the cir- 

 cumference of that opening, to be spread on the posterior face of the epi- 

 glottis and the internal face of the arytenoid cartilages, to dip into the 

 ventricles, pass above the vocal cords, line the inner face of the criooid 

 curtilage, and, finally, to be prolonged into the tracheal tube. Its deep face 

 adheres closely to the parts it covers, except in the lateral ventricles. The 

 free face is perfectly tense, and is covered with stratified tcsselated epi- 

 thelium at the epiglottis and vocal cords, but only with ciliated epithelium 

 elsewhere. 



The glandulce of the larynx are racemose, and are numerous on the 

 posterior face of the epiglottis, where they are lodged in the minute depres- 

 sions of the cartilage ; they are also found on the arytenoid cartilages and 

 the aryteno-epiglottidean folds. The mucous membrane of the larynx 

 possesses an exquisite sensibility, owing to which admission to the air- 

 passage is denied to the solid or liquid alimentary particles, which, during 

 deglutition, might deviate from their normal course and pass into this 

 opening. The slightest touch brings into play this sensibility, and deter- 

 mines an energetic reflex excitation of the constrictor muscles of the larynx 

 and chest ; from this results the almost complete occlusion of the larynx al 

 tube, and a violent cough which expels the substances whose contact has 

 occasioned the irritation of the membrane. Everyone has experienced the 

 is of this reflex action, and knows by experience the groat sensibility of 

 the larynx. 



4. Vesseh and nerves. Blood is carried to the larynx by the larynjcal 

 itrf'-ries, which pass between the cricoid and the posterior border of the 

 thyroid cartilages. Their branches spread over the vcntrical of the glottis 

 and the thyro-arytenoid muscle, to be expended in the substance of the 

 muscles and mucous membrane. The terminal ramitimtii us form red 

 plexuses on certain parts of the larynx. The rrin* are satellites of the 

 arteries. The li/inphnfii-g form a superficial and a submucous network. 



The pneumogastric furnishes the larynx with its principal nerves the 

 superior and inferior laryn>jil. The first is distributed to the upper part 

 < 1 the organ and to the entrance to the glottis, endowing the mucous 

 membrane with that high degree of sensibility that distinguishes it. The 

 second is more especially a motor nerve, and supplies all the muscles, 

 i't the crico-thyroid muscle. A filament of the recurrent nerve is 

 distributed in the mucous membrane of the subglottal portion, nnd to tho 



