436 



VOICE AND SPEECH 



the superior vocal chords they are covered with a very thin and closely 

 adherent mucous membrane. The mucous membrane over the borders 

 of the chords is covered with flattened epithelium without cilia. There 

 are no mucous glands in the membrane covering either the superior or 



the inferior chords. The inferior vocal 

 chords alone are directly concerned in the 

 production of the voice. 



Muscles of the Larynx. The muscles 

 of the larynx are classified as extrinsic and 

 intrinsic. The extrinsic muscles are at- 

 tached to the outer surface of the larynx 

 and to adjacent organs, such as the hyoid 

 bone and the sternum. They are con- 

 cerned chiefly in the movements of eleva- 

 tion and depression of the larynx. The 

 intrinsic muscles are attached to the differ- 



UB ii^ '*$ 1.7 ent P ar ^ s f tne larynx, and by their action 

 ".//' I on the articulating cartilages are capable of 



modifying the tension of the vocal chords. 

 The vocal chords can be rendered tense 

 or lax by muscular action. Their fixed 

 point is in front, where their extremities, 

 attached to the thyroid cartilage, are nearly 

 or quite in contact with each other. The 



- virtual seaio,,. of tkeku- J*^ cartilages, to which they are 

 man larynx, showing the vocal chords attached posteriorly, present a movable 



30. 



(Sappey). 



articulation with the cricoid cartilage; and 



, .. .... 



the cricoid, which is narrow in front, and 

 j s w jd e behind, where the arytenoid carti- 



* 



I, ventricle of the larynx; 2, superior 



vocal chord; 3 , inferior vocal chord; 

 4, arytenoid cartilage; 5> section of 



the arytenoid muscle; 6, 6, inferior por- 



tion of the cavity of the larynx ; 7, sec- lages are attached, presents a movable 

 Soi d f ca r ,a^ te 8,LcC i0 o n f thl *! articulation with the thyroid cartilage. It 

 terior portion of the cricoid cartilage ; is evident, therefore, that muscles acting 



9, superior border of the cricoid car- ,1 j ., 



tilage; 10, section of the thyroid car- n the CHCOld Can CaUSC it to SWing on 



tilage; n, n, superior portion of the its tWO points of articulation with the hl- 



cavity of the larynx ; 12, 13, arytenoid r r . . . . . . 



gland; 14,16, epiglottis; 15, 17, adipose tenor cornua of the thyroid, raising the 

 tissue; 18, section of the hyoid bone; anterior portion and approximating it to 



19, 19, 20, trachea. 



the lower edge of the thyroid ; and as a 



consequence, the posterior portion, which carries the arytenoid carti- 

 lages and the posterior attachments of the vocal chords, is depressed. 

 This action would, of course, increase the distance between the aryte- 

 noid cartilages and the anterior portion of the thyroid, elongate the vocal 

 chords, and subject them to a certain degree of tension. Experiments 



