6O2 



ARRANGEMENT OF THE LARYNX. 



The intimate approximation of the vocal bands is effected by bringing 

 the vocal processes of the arytenoid cartilages close together. To this 

 end the latter must be rotated inward and downward by a forward 

 and upward movement on the part of the muscular processes affected 

 through the vocal or internal thyro-arytenoid muscles. These muscles, 

 which are applied to the elastic borders of the vocal bands, and in fact 

 are embedded in their substance and whose fibers extend to the outer 

 borders of the arytenoid cartilages, rotate the latter so that their vocal 



Corn 



Corn 

 inf. 



FIG. 206. Posterior View of the Larynx, with the 

 Muscles: E, epiglottis with the cushion (WO; 

 C.-W., cartilages of Wrisberg; C.-S., cartilages of 

 Santorini; Cart, eric., cricoid cartilage; Cornu 

 sup., superior cornu, Cornu inf., inferior cornu of 

 the thyroid cartilage; M. ar. tr', transverse aryte- 

 noid muscle; Mm. ar. obi., oblique arytenoid mus- 

 cles; M. cr. aryt. post., posterior crico-arytenoid 

 muscle; Pars cart., cartilaginous portion of the 

 trachea; Pars memo., membranous portion of the 

 trachea. 



FIG. 207. Nerves of the Larynx: O. h., hyoid bone; 

 C. th., thyroid cartilage; C. c., cricoid cartilage; 

 Tr., trachea; M. th.-ar., thyro-arytenoid muscle; 

 M. cr. ar. p. posterior crico-arytenoid muscle; 

 M. cr. ar. 1., lateral crico-arytenoid muscle; M . cr. 

 lh., crico-thyroid muscle; N. LAR. SUP. V., supe- 

 rior laryngeal branch of the vagus; R. I., internal 

 branch; R. E., external branch; N. L. R. V., 

 recurrent laryngeal branch of the vagus; R. I. N. 

 L. R., its internal branch; R. E. N. L. R., its ex- 

 ternal branch. 



processes must move inward. The glottis between the vocal bands is 

 thus narrowed to a slit, while a broad, triangular opening remains be- 

 tween the bases of the arytenoid cartilages (Fig. 210). 



The lateral crico-arytenoid muscle is inserted into the anterior border 

 of the articular surface of the arytenoid cartilage; hence, it can only 

 draw the cartilage forward. Some investigators, however, believe that 

 it also can effect a rotation of the arytenoid cartilage similar to that 

 of the vocal or internal thyro-arytenoid muscle, with the difference that 

 the vocal process are not brought so close together. 



Pathological. Paralysis of the muscles effecting approximation of the vocal 

 bands results in loss of voice. 



