CARTILAGES OF THE LARYNX. 705 



approximated, to the mouth of a pitcher (apvtatva-ti&os, like a pitcher). They are 

 t\vo in number, and situated at the upper border of the cricoid cartilage, at the 

 back of the larynx. Each cartilage is pyramidal in form, and presents for ex- 

 amination three surfaces, a base, and an apex. 



The posterior surface is triangular, smooth, concave, and lodges part of the 

 Arytenoid muscle. 



The anterior surface, somewhat convex and rough, gives attachment to the 

 Thyro-arytenoid muscle, and to the false vocal cord. 



The internal surface is narrow, smooth, and flattened, covered by mucous mem- 

 brane, and lies almost in apposition with the cartilage of the opposite side. 



The base of each cartilage is broad, and presents a concave smooth surface, for 

 articulation with the cricoid cartilage. Of its three angles, the external one is 

 short, rounded, and prominent, receiving the insertion of the posterior and lateral 

 Crico-arytenoid muscles. The anterior one, also prominent, but more pointed, 

 gives attachment to the true vocal cord. 



The apex of each cartilage is pointed, curved backwards and inwards, and 

 surmounted by a small conical-shaped, cartilaginous nodule, corniculum laryngis 

 (cartilage of Santorini). This cartilage is sometimes- united to the arytenoid, and 

 serves to prolong it backwards and inwards. To it is attached the aryteno- 

 epiglottidean fold. 



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

 cartilaginous 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 (a-ryteno-epigloltidean fold) ] they give rise to the small whitish eleva- 

 tions 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. During respiration, its direction is vertically upwards, its free 

 extremity curving forwards towards the base of the tongue ; but when the larynx 

 is drawn up beneath the base of the tongue during deglutition, it is carried 

 downwards and backwards, so as to completely close the opening of the larynx. 

 Its free extremity is broad and rounded ; its attached end is long and narrow, 

 and connected to the receding angle between the two ala3 of the thyroid cartilage, 

 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 forwards towards the tongue, and 

 covered by mucous membrane, which is reflected on to the sides and base of 

 this organ, forming a median and two lateral folds, the glosso-epiglottidean 

 ligaments. 



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

 from above downwards, and covered by mucous membrane; when this 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 epiglottis, cuneiform cartilages, and cornicula laryngis are 

 composed of yellow cartilage, which shows little tendency to ossification ; but the 

 other cartilages resemble in structure the costal cartilages, becoming more or less 

 ossified in old age. 



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

 thyroid cartilage with the os hyoides; and intrinsic, as those connecting the 

 several cartilaginous segments to each other. 



The ligaments connecting the thyroid cartilage with the os hyoides are 

 three in number ; the thyro-hyoid membrane, and the two lateral thyro-hyoid 

 ligaments. 



The thyro-hyoid membrane is a broad, fibro-elastic, membranous layer, attached 

 45 



