484 MUCOUS MEMBRANE OF THE LARYNX. 



capacity of that cavity, and change its form ; and to approximate 

 the epiglottis and the arytenoid cartilage." 



Mucous Membrane. The larynx is lined by the mucous mem- 

 brane, which is continued from the mouth and pharynx, and pro- 

 longed onwards through the trachea and bronchi to the bronchial 

 cells. The chorda? vocales form two horizontal projections of the 

 mucous membrane, and constitute the lateral boundaries of the 

 glottis, or rima glottidis. Immediately above the horizontal projec- 

 tion of the chorda vocalis, at each side, is a depressed fossa, the 

 ventricle of the larynx. The superior boundary of the ventricle is 

 an arched border of mucous membrane, which is very incorrectly 

 termed the superior chorda vocalis. If the rounded extremity of a 

 probe be introduced into the ventricle of the larynx, and then directed 

 upwards, it will enter a considerable pouch, which has been recently 

 described by Mr. Hilton as the sacculus laryngis.* From the ven- 

 tricle of the larynx the sacculus is continued upwards, nearly as 

 high as the upper border of the thyroid cartilage, and sometimes 

 beyond it. When dissected from the interior of the larynx it is 

 found covered by the aryteno-epiglottideus muscle and a fibrous 

 membrane, which is attached to the superior chorda vocalis below ; 

 to the epiglottis in front; and to the upper border of the thyroid 

 cartilage above. If examined from the exterior of the larynx, it 

 will be seen to be covered by the thyro-epiglottideus muscle. On 

 the surface of its mucous membrane are the openings of sixty or 

 seventy small follicular glands, which are situated in the sub-mucous 

 tissue, and give to its external surface a rough and ill-dissected ap- 

 pearance. This mucous secretion is intended for the lubrication of 

 the chordas vocales, and is directed upon them by two small valvular 

 folds of mucous membrane, which are situateid at the entrance of 

 the sacculus. 



The Entrance of the larynx is formed by two folds of mucous 

 membrane, stretched between the apices of the arytenoid cartilages 

 and the sides of the epiglottis. The arytenoid glands and superior 

 aryteno-epiglottidean muscles are situated within these folds. 



* This sac was discovered and described by Mr. Hilton before he was aware that it 

 had already been pointed out by the older anatomists. I myself made a dissection, 

 which I still possess, of the same sac in an enlarged state during the month of August, 

 1837, without any knowledge either of Mr. Hilton's labours, or Morgagni's account. 

 The sac projected considerably above the upper border of the thyroid cartilage, and the 

 extremity had been snipped off on one side in the removal of the muscles. The larynx 

 was presented to me by Dr. George Moore of Camberwell : he had obtained it from a 

 child who died of bronchial disease ; and he conceived that this peculiar disposition of 

 the mucous membrane might possibly explain some of the symptoms by which the case 

 was accompanied. Cruveilhier made the same discovery in equal ignorance of Mor- 

 gagni's description, for we read in a note at page 677, vol. ii. of his Anatomic Descrip. 

 live, " J'ai vu pour la premiere fois cette arriere cavite chez un individu affecte de 

 phthisie laryngee, ou elle etait tres-developpee. Je fis des recherches sur le larynx 

 d'autres individus, et je trouvai que cette disposition etait constante. Je ne savais pas 

 alors que Morgagni avait indique et fait representer la meme disposition." Cruveilhier 

 compares its form very aptly to a "Phrygian casque," and Morgagni's figure, Advers. 

 1, Epist. Anat. 3, plate 2, fig. 4, has the same appearance. But neither of these anato- 

 mists notice the follicular glands described by Mr. Hilton. 



