772 



ORGANS OF YOICE AND RESPIRATION. 



border of the inner surface of the hyoid bone: being separated from the poste- 

 rior surface of the hyoid bone by a synovial bursa. It is thicker in the middle 

 line than at either side, in which situation it is pierced by the superior laryn- 

 geal vessels and nerve. 



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

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

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

 triticea\ sometimes bony, is found in each. 



The ligaments connecting the thyroid cartilage to the cricoid are also three 

 in number; the crico-thyroid membrane, and the capsular ligaments and syno- 

 vial membrane. 



The crico-thyroid membrane is composed mainly of yellow elastic tissue. It is 

 of triangular shape; thick in front, where it connects together the contiguous 

 margins of the thyroid and cricoid cartilages; thinner at each side, where it 

 extends from the superior border of the cricoid cartilage, to the inferior margin 

 of the true vocal cords, with which it is closely united in front. 



The anterior portion of the crico-thyroid membrane is convex, concealed on 

 each side by the Crico-thyroid muscle, subcutaneous in the middle line, and 

 crossed horizontally by a small anastomotic arterial arch, formed by the junc- 

 tion of the two crico-thyroid arteries. 



The lateral portions are lined internally by mucous membrane, and covered 

 by the lateral Crico-arytenoid and Thyro-arytenoid muscles. 



A capsular ligament incloses the articulation of the inferior cornu of the 

 thyroid with the cricoid cartilage on each side. The articulation is lined by 

 synovial membrane. 



The ligaments connecting the arytenoid cartilages to the cricoid, are two 

 thin and loose capsular ligaments connecting together the articulating surfaces 

 lined internally by synovial membrane, and strengthened behind by a strong 



posterior crico-arytenoid liga- 



Fig. 424. The Larynx and adjacent parts, as seen ment, which extends from the 



cricoid to the inner and back 



part of the base of the aryte- 

 r . , ., J 



noid cartilage. 



The ligaments of the epiglot- 

 tis are the hyo-epiglottic, the 

 thyro-epiglottic, and the three 

 glosso-epiglottic folds of mu- 

 cous membrane which connect 

 the epiglottis to the sides and 

 base of the tongue. The latter 

 have been already described. 



The hyo-epi glottic ligament is 

 an elastic fibrous band, which 

 extends from the anterior sur- 

 face of the epiglottis, near its 

 apex, to the posterior surface 

 of the body of the hyoid bone. 

 The thyro-cpiglottic ligannut 

 is a long, slender, elastic cord, 



which connects the apex of the epiglottis with the receding angle of the thyroid 



cartilage, immediately beneath the median notch, above the attachment of the 



vocal cords. 



Interior of the larynx. The superior aperture of the larynx (Fig. 424) is a 



triangular or cordiform opening, wide in front, narrow behind, and sloping 



obliquely downwards and backwards. It is bounded in front by the epiglottis; 



behind, by the apices of the arytenoid cartilages, and the cornicula laryngis; 



and laterally, tfy a fold of mucous membrane, inclosing ligamentous and mus- 



