PHONATION; ARTICULATE SPEECH. 



577 



around its vertical axis; the inferior and obliquely 'directed fibers 

 draw the cartilage downward and inward. As a result of the action 

 of the muscle in its entirety, the vocal process is turned upward and 

 outward, and as the vocal band is carried with it the glottis is widened, 

 a condition necessary to the free entrance of air into the lungs (Fig. 



FIG. 263. POSTERIOR VIEW OF THE 

 MUSCLES OF THE LARYNX. i. 

 Posterior crico-arytenoid muscle. 

 2, 3, 4. Different fasciculi of the 

 arytenoid muscle. 5. Aryteno- 

 epiglottidean muscle. (Sappey.} 



265). Since the contraction of the 

 crico-arytenoid has this result, it is 

 generally spoken of as the abductor or 

 respiratory muscle. 



The lateral crico-arytenoid muscle 

 arises from the side of the cricoid 

 cartilage. From this point its fibers 

 are directed upward and backward to 



FIG. 264. LATERAL VIEW OF THE 

 MUSCLES or THE LARYNX, i. 

 Body of the hyoid bone. 2. Verti- 

 cal section of the thyroid cartilage. 

 3. Horizontal section of the thyroid 

 cartilage turned downward to show 

 the deep attachment of the crico- 

 thyroid muscle. 4. Facet of articu- 

 lation of the small cornu of the 

 thyroid cartilage with the cricoid 

 cartilage. 5. Facet on the cricoid 

 cartilage. 6. Superior attachment of 

 the cri co-thyroid muscle. 7. Pos- 

 terior crico-arytenoid muscle. 8, 

 10. Arytenoid muscle. 9. Thyro- 

 arytenoid muscle. n. Aryteno- 

 epiglottidean muscle. 12. Middle 

 thyro-hyoid ligament. 13. Lateral 

 thyro-hyoid ligament. (Sappey.) 



be inserted into the external process 

 of the arytenoid. Its action is to draw the arytenoid cartilage for- 

 ward and inward, thus approximating and relaxing the vocal band. 



The thyro-arytenoid muscle arises from the inferior two-thirds 

 of the inner surface of the thyroid cartilage just external to the 

 median line. From this origin the fibers pass backward and outward, 

 37 



