250 THE VISCERA. 



fibres pass craniolaterad, converging. The lateral fibres are 

 nearly longitudinal in direction. 



Insertion. The dorsal border of the caudal end of the 

 arytenoid cartilage (). 



Action. Moves the arytenoid on its oblique articulation 

 with the thyroid. The apex of the arytenoid is thus carried 

 laterad, and the vocal cords are separated so as to widen the 

 glottis. 



FIG. 105. MUSCLES OF THE LARYNX, AS EXPOSED BY REMOVAL OF MOST OF 



THE LEFT HALF OF THE THYROID CARTILAGE. 



i. epiglottis; 2. portion of the thyroid cartilage (cut); 3, cricoid cartilage; 4, 

 arytenoid cartilage; 5, trachea, a, M. arytenoideus transversus; , M. cricoarytenoi- 

 deus posterior; c, M. cricoarytenoideus lateralis; d, M. thyreoarytenoideus. 



M. artyenoideus transversus (Fig. 105, a). A small 

 unpaired muscle running transversely between the caudal ends 

 of the arytenoid cartilages, just beneath the mucous membrane 

 and parallel to the cranial border of the cricoid cartilage. 



M. glossoepiglotticus. A small longitudinal muscle, lying 

 by the side of its fellow in the frenulum of the epiglottis. 



Origin. The median fibrous septum of the tongue. 



Insertion. The dorsal (cranial) surface of the epiglottic 

 cartilage in the median line near its attached border. 



Action. Draws the epiglottis craniad. 



M. hyoepiglotticus is a small bundle of parallel fibres lying 

 in the frenulum of the epiglottis craniad and dorsad of the body 

 of the hyoid bone. 



Origin. The lateral end of the cranial surface of the body 

 of the hyoid. The two muscles pass craniodorsad, converging, 

 and unite with the preceding. 



Insertion with the preceding. (The lateral portion of the 

 muscle may continue craniad to the tongue as a second part of 

 the hyoglossus.) 



Action. Like the preceding. 



