MUSCLES OF THE LARYNX. 



709 



Fig. 359. Muscles of Larynx, Side View. 

 Bight Ala of Thyroid Cartilage removed. 



The Grico-arytsenoideus lateralis is smaller than the preceding, and of an 

 oblong form. It arises from the upper border of the side of the cricoid cartilage, 

 and, passing obliquely upwards and 

 backwards, is inserted into the outer 

 angle of the base of the arytenoid 

 cartilage, in front of the preceding 

 muscle. 



The Thyro-arytxnoideus is a broad, 

 flat muscle, which lies parallel with 

 the outer side of the true vocal cord. 

 It arises in front from the lower 

 half of the receding angle of the 

 thyroid cartilage, and from the 

 crico-thyroid membrane. Its fibres 

 pass horizontally backwards and 

 outwards, to be inserted into the 

 base and anterior surface of the 

 arytenoid cartilage. This muscle 

 consists of two fasciculi. The in- 

 ferior, the thickest, is inserted into 

 the anterior angle of the base of the 

 arytenoid cartilage, and into the ad- 

 jacent portion of its anterior surface; 

 it lies parallel with the true vocal 

 cord, to which it is occasionally ad- 

 herent. The superior fasciculus, 

 the thinnest, is inserted into the 

 anterior surface and outer border of 

 the arytenoid cartilage above the 

 preceding fibres ; it lies on the outer 

 side of 'the sacculus laryngis, imme- 

 diately beneath its mucous lining. 



The Arytsenoideus is a single 

 muscle, filling up the posterior con- 

 cave surface of the arytenoid carti- 

 lages. It arises from the posterior 

 surface and outer border of one 

 arytenoid cartilage, and is inserted 

 into the corresponding parts of the 

 opposite cartilage. It consists of 

 three planes of fibres ; two oblique, 

 and one transverse. The oblique 

 fibres, the most superficial, form 

 two fasciculi, which pass from the 

 base of one cartilage to the apex of 

 the opposite one. The transverse 

 fibres, the deepest and most nume- 

 rous, pass transversely across be- 

 tween the two cartilages ; hence the 

 Arytaenoideus was formerly con- 

 sidered as several muscles, under 

 the names of transversi and obliqui. 

 A few of the oblique febres are oc- 

 casionally continued round the outer 

 margin of the cartilage, and blend 

 with the Thyro-arytenoid or the 

 Arytseno-epiglottideus muscle. 



Fig. 360. Interior of the Larynx, seen from 

 above. (Enlarged.) 



