906 



THE ORGANS OF VOICE 



mainly of elastic fibres. It is attached l)elo\v to the upper margin of the thyroid 

 cartilage, and above to the upper and hinder margin of the hyoid bone. It presents 

 a thick central portion (stretching between the median notch and the body of the 

 hyoid bone), and thinner lateral jiortions, looser in texture, which are pierced by 

 the superior laryngeal nerves and arteries. Posteriorly, the membrane is loosely- 

 connected with the sui)erior cornua of the tliyroid cartilage, and above these it is 

 bouniled on each side by thickened bands, the thyro-hyoid ligaments, wliich pass 

 between their tips and the greater cornua of the hyoid bone. 



A little grain-like cartilage (cartilago triticea) is usually imbedded in this band 

 just above the superior thyroid cornu. 



The central portion of the membrane is mainly subcutaneous, a bursa interven- 

 ing where it is overhung by the body of the hyoid bone. 



Its lateral portions are covered by the thyro-hyoid muscles. Posteriorly it is 

 separated from the epiglottis by the mucous membrane at the base of the tongue 

 and the areolar fatty tissue already described. It is pierced by the internal laryn- 

 geal vessels and nerves. 



The crico-thyroid membrane (intrinsic) is composed chiefly of elastic tissue. 

 It presents a prominent rounded median portion overlapped slightly b}' the crico- 

 thyroid muscles, but between these muscles it is subcutaneous. It is crossed by a 

 small anastomotic arch formed by the crico-thyroid twigs of the superior laryngeal 

 artery; one or two small holes, which pass through it, transmit vessels from the 

 arch to the interior of the larynx. 





 Fig. 527. — Superior View of the Cartilages of the Larynx. 



ANTERIOR SURFACE OF 

 CRICOID CARTILAGE 



True vocal cord 

 Crico-thyroid 

 membrane 



CRICOID CARTILAGE 



VOCAL PROCESS 



ANTERIOR SURFACE OF 



ARYTENOID CARTILAGE 



INFERIOR CORNU OF 



THYROID CARTILAGE 



SUPERIOR CORNU OF 

 THYROID CARTILAGE 



POSTERIOR SURFACE OF 

 ARYTENOID CARTILAGE 



Anterior portion of 

 crico-thyroid membrane 



Cut edge of 

 crico-thyroid membrane 



SUPERIOR BORDER OF 

 THYROID CARTILAGE 



CRICO-THYROID 



ARTICULATION 

 SUPERIOR BORDER OF 



CRICOID CARTILAGE 



CORNICULUM LARYNGIS 



POSTERIOR SURFACE OF 

 CRICOID CARTILAGE 



This median portion of the membrane stretches between the borders of the two 

 cartilages. The lateral and thinner portions pass upwards from the inner border 

 of the upper margin of the cricoid cartilage in contact with the laryngeal mucous 

 membrane, and within the embrace of the thyroid cartilage, to form the true vocal 

 cords or inferior thyro-arytenoid ligaments. These elastic liands extend from 

 the vocal processes of the arytenoid cartilages to the retiring angle of the thyroid 

 near its centre. 



The lateral portions of tliis membrane are covered superficially by the thyro- 

 arytenoid and lateral crico-arytetioid muscles. 



The superior thyro-arytenoid ligaments are contained within the arched folds 

 of mucous membrane which form the false vocal cords. They consist of a few 

 bundles of fibrous tissue. 



The crico-arytenoid nr transverse ligament has been already sufficiently 

 noticed. 



The Joints of the Larynx.— Tlie crico-thyroid joints are lined l)y a synovial 

 membrane, embraced l)ya thin capsule of radiating filires, and often strengthened 

 posteriorly ])y a well-marked fibrous band. They ])ennit of movement l)etween the 

 two cartilages U])on an ax'is i)assing transversely through both joints, and a limited 

 gliding of the cricoid upwards and l)ackwards. As can be sliown on the living 

 body, the (Ticoid is the cartilage which swings between the inferior thyroid cornua. 



I 

 J 



