VOICE ANATOMY OF THE VOCAL APPARATUS. 



457 



Fig. 197. 



roid, and of a muscle of the same name. These folds are called infe- 

 rior ligaments or lips of the glottis or inferior vocal cords. They are 

 represented by T V, in Fig. 196, and B B, Fig. 197. Between these 

 two clefts are the sinuses or ventricles of the larynx, V V, Fig. 197. 

 The inferior, exterior, and superior sides of these are formed ^by the 

 thyro-arytenoid muscles. By means of these ligaments superior and 

 inferior the lips of the superior and inferior aperture are perfectly 

 free, and unencumbered in their action. 1 



Anatomical descriptions will be found to give different significations 

 to the word glottis. Some have applied it to 

 the upper cleft ; others to the lower ; some to 

 the ventricles of the larynx; and others to the 

 whole space comprised between the inferior liga- 

 ments and top of the larynx. It is now, gene- 

 rally perhaps, restricted to the part of the larynx 

 engaged in the production of voice, or usually 

 considered to be so engaged, that is, the space 

 between the inferior ligaments plus the liga- 

 ments themselves; and in this signification it 

 will be employed here. 



The mucous membrane, which lines the larynx, 

 is continuous above with that of the mouth; 

 below, with that of the trachea. It contains 

 several mucous follicles, some of which are ag- 

 glomerated near the superior ligaments of the 

 glottis and the environs of the ventricles of the 

 larynx, seeming to constitute distinct organs, 

 which have been called arytenoid glands. A 

 similar group exists between the epiglottis be- 

 hind, and the os hyoides and thyroid cartilage before, which has been 

 termed the epiglottic gland. The uses of this body are not clear. M. 

 Magendie 2 conceives, that it favours the frequent slidings of the thyroid 

 cartilage over the posterior surface of the os hyoides; keeps the epi- 

 glottis separated above from this bone; and, at the same time, furnishes 

 it a very elastic support, which may aid it in the functions it has to 

 execute, connected with voice and deglutition. 



The larynx is capable of being moved as a whole, as well as in its 

 component cartilages. It may be raised, depressed, or carried forwards 

 or backwards. The movements, however, which are most concerned in 

 the production of voice, are those effected by the action of the intrinsic 

 muscles, as they have been termed. These are, 1st. The crico-thyroid, 

 a thin, quadrilateral muscle, which arises from the anterior surface of 

 the cricoid cartilage, and is inserted into the lower and inner border of 

 the thyroid. M. Magendie 3 affirms, that its use is not, as generally ima- 

 gined, to depress the thyroid on the cricoid, but to elevate the cricoid, 

 approximate it to the thyroid, and even make it pass slightly under its in- 

 ferior margin. The effects of its contraction must be to render the vocal 



1 Hilton, Guy's Hospital Reports, No. v. October, 1837, p. 519, and Leidy, American 

 Journal of the Medical Sciences, p. 142, July, 1846. 



2 Precis, &c., i. 237. 3 Ibid., i. 236, 



Scheme of the Lar ynx. 



