530 



MUSCLES OF THE LARYNX. 



transversus. To which are also added the ihyro-epiglotti- 

 deuSj aryteno-epiglottideus. 



The thyro-arytenoideus, within the vocal case, arises 

 near the angle of the thyroid cartilage on its posterior sur- 

 FIG. 163. face, and proceeds backward and out- 



ward, along the sides of the rima glot- 

 tidis, to be inserted into the anterior 

 and outer margin of the arytenoid car- 

 tilage. Function. To bring the ary- 

 tenoid cartilages forward, and thus 

 relax the vocal chords. These muscles 

 are regarded as the most important in 

 the production of voice. They are con- 

 cealed by the alee of the thyroid car- 

 tilage, and are connected with and run 

 along the vocal ligaments. 

 Crico-arytenoideus posticus. Dissection. Open the pha- 

 rynx by a vertical incision and dissect off the mucous 

 membrane. 



FIG. 164. This muscle will then be seen to 



arise from the posterior surface of the 

 cricoid cartilage, and to pass obliquely 

 upward and outward, as a flat and 

 strong muscle, to be inserted into the 

 posterior and outer part of the base 

 of the arytenoid cartilage. 



Function. To antagonize the pre- 

 ceding muscle by drawing backward 

 the arytenoid cartilages and making 

 tense the vocal chords. 



The crico-arytenoideus lateralis 

 (Fig. 163) arises from the side of the cricoid at its upper 



F,G. 163 represents two of the Muscles of the Larynx, a Epiglottis. 6 Cri- 

 coid cartilage, c Thyroid cartilage, d Crico-arytenoideus lateralis mus 

 t Thyro-arytenoideus. 



FIG 164 represents the Muscles on the posterior Larynx, a Epiglottis. 6 

 Thyroid cartilage, c Cricoid cartilage, d Crico-arytenoideus-posticus. * 

 Arytenoideus transversus. / Arytenoideus obliquus. 



