MUCOUS MEMBRANE. 547 



of that cavity, and change its form ; and to approximate the epiglottis 

 and the arytenoid cartilage." 



Mucous membrane. The aperture of the larynx is a triangular, or 

 cordiform opening, broad in front and narrow behind ; bounded ante- 

 riorly by the epiglottis, posteriorly by the arytenoideus muscle, and on 

 either side by a fold of mucous membrane stretched between the side 

 of the epiglottis and the apex of the arytenoid cartilage. On the mar- 

 gin of this aryteno-epiglottidean fold the cuneiform cartilage forms a 

 prominence more or less distinct. The cavity of the larynx is divided 

 into two parts by an oblong constriction produced by the prominence 

 of the chordae vocales. That portion of the cavity which lies above 

 the constriction is broad and triangular above, and narrow below ; that 

 which is below it is narrow above and broad and cylindrical below, 

 the circumference of the cylinder corresponding with the ring of the 

 cricoid ; while the space included by the constriction is a narrow, tri- 

 angular fissure, the glottis or rima glottidis. The form of the glottis is 

 that of an isosceles triangle, bounded on the sides by the chordae vo- 

 cales and inner surface of the arytenoid cartilages, and behind by the 

 arytenoideus muscle. Its length is greater in the male than in the fe- 

 male, and in the former measures somewhat less than an inch. Imme- 

 diately above the prominence caused by the chorda vocalis, and ex- 

 tending nearly its entire length on each side of the cavity of the larynx, 

 is an elliptical fossa, the ventricle of the larynx. This fossa is bounded 

 below by the chorda vocalis, which it serves to isolate, and above by a 

 border of mucous membrane folded upon the lower edge of the supe- 

 rior thyro-arytenoid ligament. The whole of the cavity of the larynx 

 with its prominences and depressions, is lined by mucous membrane, 

 which is continuous superiorly with that of the mouth and pharynx, 

 and inferiorly is prolonged through the trachea and bronchial tubes 

 into the air cells of the lungs. In the ventricles of the larynx the 

 mucous membrane forms a csecal pouch of variable size, termed by 

 Mr. Hilton the sacculus laryngis.* The sacculus laryngis is directed 



* This sac was 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 Mor- 

 gagni'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 dis- 

 ease ; and he conceived that this peculiar disposition of the mucous membrane 

 might possibly explain some of the symptoms by which the case was accom- 

 panied. Cruveilhier made the same observation in equal ignorance of Mor- 

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

 Descriptive, " J'ai vu pour la premiere fois cette arriere cavite chez un indi- 

 vidu affecte de phthisie laryngee, ou elle etait tres-developpee. Je fis des re- 

 cherches 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 repre- 

 senter la meme disposition." Cruveilhier compares its form very aptly to a 



