958 THE ORGANS OF VOICE AND RESPIRATION. 



attached the aryteno-epiglottidean folds. They are sometimes united to the aryte- 

 noid cartilages. 



The cuneiform cartilages (cartilages of Wrisberg) are two small, elongated, car- 

 tilaginous bodies, placed one on each side, in the fold of mucous membrane which 

 extends from the apex of the arytenoid cartilage to the side of the epiglottis 

 (aryteno-epiglottidean fold) ; they give rise to small whitish elevations on the inner 

 surface of the mucous membrane, just in front of the arytenoid cartilages. 



The epiglottis is a thin lamella of fibro-cartilage, of a yellowish color, shaped 

 like a leaf, and placed behind the tongue in front of the superior opening of the 

 larynx. Its free extremity is broad and rounded ; its attached part is long, nar- 

 row, and connected to the receding angle between the two alse of the thyroid car- 

 tilage, just below the median notch, by a long, narrow ligamentous band, the 

 thyro-epiglottic ligament. It is also connected to the posterior surface of the body 

 of the hyoid bone by an elastic ligamentous band, the hyo-epiglottic ligament. 



Its anterior or lingual surface is curved forward, toward the tongue, and 

 covered at its upper, free part by mucous membrane, which is reflected on to the 

 sides and base of the organ, forming a median and two lateral folds, the glosso- 

 epiglottidean folds. The depressions between the epiglottis and the base of the 

 tongue, on either side of the median fold, are named the valleculce. The lower part 

 of its anterior surface lies behind the hyoid bone, the thyro-hyoid membrane, and 

 upper part of the thyroid cartilage, but is separated from these structures by a 

 mass of fatty tissue. 



Its posterior or laryngeal surface is smooth, concave from side to side, concavo- 

 convex from above downward; its lower part projects backward as an elevation, 

 the tubercle or cushion ; when the mucous membrane is removed, the surface of 

 the cartilage is seen to be studded with a number of small mucous glands, which 

 are lodged in little pits upon its surface. To its sides the aryteno-epiglottidean 

 folds are attached. 



Structure. The cuneiform cartilages, the epiglottis, and the apices of the aryte- 

 noids are composed of yellow fibro-cartilage, which shows little tendency to cal- 

 cification ; on the other hand, the thyroid, cricoid, and the greater part of the 

 arytenoids consist of hyaline cartilage, arid become more or less ossified as age 

 advances. Ossification commences about the twenty-fifth year in the thyroid car- 

 tilage, somewhat later in the cricoid and arytenoids ; by the sixty-fifth year these 

 cartilages may be completely converted into bone. The cornicula laryngis consist 

 of white fibro-cartilage, which becomes osseous about the seventieth year. 



Ligaments. The ligaments of the larynx are extrinsic i. e., those connecting 

 thj thyroid cartilage and epiglottis with the hyoid bone, and the cricoid cartilage 

 with the trachea; and intrinsic, those which connect the several cartilages of the 

 larynx to each other. 



The ligaments connecting the thyroid cartilage with the hyoid bone are three 

 in number the thyro-hyoid membrane, and the two lateral thyro-hyoid liga- 

 ments. 



The thyro-hyoid membrane, or middle thyro-hyoid ligament, is a broad, fibro- 

 elastic, membranous layer, attached below to the upper border of the thyroid 

 cartilage, and above to the posterior border of the body and greater cornua of the 

 hyoid bone, thus passing behind the postero-inferior surface of the hyoid, and 

 being separated from it by a synovial bursa, which facilitates the upward move- 

 ment of the larynx during deglutition. It is thicker in the middle line than at 

 either side, and is pierced, in the latter situation, by the superior laryngeal vessels 

 and the internal branch of the superior laryngeal nerve. Its anterior surface is in 

 relation with the Thyro-hyoid, Sterno-hyoid, and Omo-hyoid muscles, and with the 

 body of the hyoid bone. 



The two lateral thyro-hyoid ligaments are rounded, elastic cords, which pass 

 between the superior cornua of the thyroid cartilage and the extremities of the 

 greater cornua of the hyoid bone. A small cartilaginous nodule (cartilago triticea], 

 sometimes bony, is frequently found in each. 



