THE RESPIRATORY SYSTEM 65 



its wall — the thyroid, cricoid, and arytenoid cartilages. 

 This may be done more easily under a dissecting micro- 

 scope. The thyroid cartilage is a band extending around 

 the antero ventral and lateral regions of the larynx. Each 

 lateral extremity gives off an anterior and posterior horn, 

 the latter joining the cricoid cartilage. The ventral por- 

 tion of the cartilage bears a median notch on the anterior 

 border, and is bound to the cricoid cartilage by the crico- 

 thyroid ligament. The cricoid cartilage has the shape of 

 a signet ring, completely encircling the air passage. It 

 is narrow ventrally, but expands dorsally into a hexagonal 

 plate whose dorsal surface is concave. It is firmly united 

 to the trachea by connective tissue. The arytenoids are a 

 pair of small cartilages articulating with the anterior bor- 

 der of the dorsal plate of the cricoid. Each attaches to the 

 dorsal end of a vocal cord. 



Exercise XVIII. Draw and label the larynx. 



