INTRINSIC MUSCLES OF LARYNX. 



775 



Fig. 426. Muscles of Larynx. Side View. 

 Eight Ala of Thyroid Cartilage removed. 



The Crico-arytsenoideus Later alis is smaller than the preceding, and of an 

 oblong form. It arises from the upper border of the side of the cricoid carti- 

 lage, 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-arytsenoideus 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 inferior, the thicker, is 

 inserted into the anterior angle of the 

 base of the arytenoid cartilage, and into 

 the adjacent portion of its anterior sur- 

 face; it lies parallel with the true vocal 

 cord, to which it is occasionally adherent. 

 The superior fasciculus, the thinner, 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 concave surface 

 of the arytenoid cartilages. 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 

 numerous, pass transversely across be- 

 tween the two cartilages; hence the 

 Arytaenoideus was formerly considered 

 as several muscles, under the names of 

 transversi and obliqui. A few of the 

 oblique fibres are occasionally continued 

 round the outer margin of the cartilage, 

 and blend with the Thyro-arj'tenoid or 

 the Aryta3no-epiglottideus muscle. 



The muscles of the epiglottis are, the 



Thyro-epiglottideus. 

 Arytaano-epiglottideus Superior. 

 Arytseno-epiglottideus Inferior. 



The Thyro-epiglottideus is a delicate 

 fasciculus, which arises from the inner 

 surface of the thyroid cartilage, just ex- 

 ternal to the origin of the Thyro-aryte- 

 noid muscle, and spreading out upon the 



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Fig. 427. Interior of the Larynx, seen 

 from above. (Enlarged.) 



