CARTILAGES AND LIGAMENTS OF LARYNX. 771 



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 examina- 

 tion 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 sarf ace 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 is 

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

 lateral Crico-arytenoid muscles. The anterior angle, 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 (aryteno-epiglottideanfold}; 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 fibre-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 ex- 

 tremity 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 alae of the thy- 

 roid cartilage, just below the median notch, by a long, narrow, Hgamentous 

 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 the 

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

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

 connect 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 liga- 

 ments. 



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

 below to the upper border of the thyroid cartilage, and above to the upper 



