THE LARYNX. 323 



cartilage, and passing upward and backward to the arytenoid, 

 is the Lateral Oico-arytenoid Muscle; cut away at its origin 

 close to the cricoid, and demonstrate its action on the aryte- 

 noid cartilage and vocal cord. 



(c) A broad muscle arising along the whole length of the 

 angle of the thyroid, whose fibers converge to the arytenoid 

 cartilage. This is the Thyro-arytenoid Muscle ; cut it across 

 near its origin, dissect it loose, and by pulling it toward its 

 origin prove its action. 



(d) On the posterior surface of the arytenoids is the small 

 Arytenoid Muscle. 



13. Cut between the arytenoid cartilages and remove one 

 of them. Examine the joint between the arytenoid and cri- 

 coid. Note the synovia lubricating the joint. 



Trim away the muscle from the arytenoid cartilage and 

 study its shape more fully. Fit it again to its place, and 

 recall the motions given by each muscle. 



14. Now examine the arytenoid cartilage and the vocal 

 cord of the opposite side ; move the arytenoid back and forth, 

 watching the vocal cord. 



15. Remove the epiglottis, and cut into it to see its 

 structure. 



16. Dissect away the parts of the other side from the in- 

 side, reviewing the above points. 



By examining the larynx we see that its cartilages are con- 

 nected with each other by ligaments which allow considerable 

 freedom of motion ; that they are also connected by muscles 

 which move them one upon another. The range of movement 

 of the arytenoid cartilages and the muscular control of these 

 cartilages is of special interest, for we see that the vocal 

 cords, so-called, are attached to these cartilages, and that the 

 chief variations of the voice are thereby regulated. 



The vocal cords are badly named. They are seen to be 



