706 



ORGANS OF VOICE AND RESPIRATION. 



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

 of the inner surface of the hyoid bone ; being separated from the posterior 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 laryngeal vessels and 

 nerve. 



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

 between the superior cornua of the thyroid cartilage, to the extremities of the 

 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 synovial 

 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 ex- 

 tends 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 junction of the 

 crico-thyroid branches on either side. 



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 side of the cricoid, 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 ligament, which extends from the cricoid to the inner and back 

 part of the base of the arytenoid cartilage. 



The ligaments of the epiglottis are the hyo-epiglottic, the thyro-epiglottic, and 

 the three glosso-epiglottic folds of mucous membrane which connect the epiglottis 

 to the sides and base of the tongue. The latter have been already described. 



The hyo-epiglottic ligament is an elastic fibrous band, which extends from the 



anterior surface of the epi- 

 Fig. 357. The Larynx and adjacent parts, glottis, near its apex, to the 



posterior surface of the body 

 of the hyoid bone. 



The thyro-epiglottic ligament 

 is a long, slender, elastic cord, 

 which connects the apex of the 

 epiglottis with the receding 

 angle of the thyroid cartilage, 

 immediately beneath the me- 

 dian notch, above the attach- 

 ment of the vocal cords. 



Interior of the Larynx. The 

 superior aperture of the larynx 

 (fig. 357) is a triangular or 

 cordiforrn opening, narrow 

 in front, wide 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, by a fold of mucous 



seen from above. 



Arytenaid. cart ' 



