MUSCLES OP THE LARYNX. 545 



Muscles. The Muscles of the larynx are eight in number: the five 

 larger are the muscles of the chordse vocales and rima glottidis ; the 

 three smaller are muscles of the epiglottis. 



The five muscles of the chordae vocales and rima glottidis are the 



Crico-thyroid, 



Crico-arytenoideus posticus, 

 Crico-arytenoideus lateralis, 

 Thyro-arytenoideus, 

 Arytenoideus. 



The Crico-thyroid muscle arises from the anterior surface of the 

 cricoid cartilage, and passes obliquely outwards and backwards to be 

 inserted into the lower and inner border of the ala of the thyroid as 

 far back as its inferior corau. 



The Crico-arytenoideus posticus arises from the depression on the 

 posterior surface of the cricoid cartilage, 

 and passes upwards and outwards to be p. 



inserted into the outer angle of the base 

 of the arytenoid. 



The Crico-arytenoideus lateralis arises 

 from the upper border of the side of 

 the cricoid, and passes upwards and 

 backwards to be inserted into the outer 

 angle of the base of the arytenoid car- 

 tilage. 



The Thyro-arytenoideus arises from 

 the receding angle of the thyroid carti- 

 lage, close to the outer side of the 

 chorda vocalis, and passes backwards 

 parallel with the cord, to be inserted 

 into the base and outer surface of the 

 arytenoid cartilage. 



The Arytenoideus muscle occupies the 



posterior concave surface of the arytenoid cartilages, between which it 

 is stretched. It consists of three planes of transverse and oblique 

 fibres ; hence it was formerly considered as several muscles, under the 

 names of transversi and obliqui. 



The three muscles of the epiglottis are the 



Thyro-epiglottideus, 

 Aryteno-epiglottideus superior, 

 Aryteno-epiglottideus inferior (Hilton's muscle). 



* A side view of the larynx, one ala of the thyroid cartilage has been removed. 

 1. The remaining ala of the thyroid cartilage. 2. One of the arytenoid carti- 

 lages. 3. One of the cornicula laryngis. 4. The cricoid cartilage. 5. The 

 crico-arytenoideus posticus muscle. 6. The crico-arytenoideus lateralis. 7. 

 The thyro-arytcnoideus. 8. The crico-thyroidean membrane. 9. One half of 

 the epiglottis. 10. The upper part of the trachea. 



2 N 



