484 



MUSCLES OF THE LARYNX. 



1 . Crico- Thyroideus, 

 Fig. 122.* Arises from the side and 



forepart of the cricoid car- 

 tilage, running obliquely up- 

 wards. 



Inserted by two portions : 

 the first, into the lower part of 

 the thyroid cartilage ; the se- 

 cond, into its inferior cornu. 



Use. To pull forwards and 

 depress the thyroid, or to ele- 

 vate and draw backwards the 

 cricoid cartilage. 



2. Crico- ArytcBuoideus Pos- 

 ticus, 

 Arises, fleshy, from the back 

 part of the cricoid cartilage ; and is 



Inserted into the posterior part of the base of the arytenoid 

 cartilage. 



Use. To open the rima glottidis a little, and, by pulling back 

 the arytenoid cartilage, to stretch the ligament so as to make it 

 tense. 



3. Crico- ArytcBnoideus Lateralis, 



Arises, fleshy, from the cricoid cartilage, laterally, where it 

 is covered by part of the thyroid, and is 



* The styloid muscles and the muscles of the tongue. 1. A portion of the 

 temporal bone of the left side of the skull, including the styloid and mastoid 

 processes, and the meatus auditorius externus. 2, 2. The right side of the lower 

 jaw, divided at its symphysis ; the left side having been removed. 3. The 

 tongue. 4. The genio-hyoideus muscle. 5. The genio-hyo-glossus. 6. The 

 hyo-glossus muscle ; well seen at the base of the tongue. 7. Its portion con- 

 nected with the oshyoides. 8. The anterior fibres of the lingualis issuing from 

 between the hyo-glossus and genio-hyo-glossus. 9. The stylo-glossus muscle, 

 with a small portion of the stylo-maxillary ligament. 10. The stylo-hyoid. 

 11. The stylo-pharyngeus muscle. 12. The os hyoides. 13. The thyro-hyoi- 

 dean membrane. 14. The thyroid cartilage. 15. The thyro-hyoideus muscle 

 arising from the oblique line on the thyroid cartilage. 16. The cricoid cartilage. 

 17. The crico-thyroidean membrane, through which the operation of laryngo- 

 tomy is performed. 18. The trachea. 19. The commencement of the oesopha- 

 gus. 



