MUSCLES OF THE LARYNX AND EPIGLOTTIS. 75 



Action, to flex the cervical vertebrae and slightly to rotate them. Nerves, 



branches from the lower cervical. 

 Scalenus Antaeus,' 20 /h?w a tubercle on the upper surface of the ist rib, 



into the transverse processes of the cervical vertebrse, from the 3d to the 6th 



inclusive. Action, to flex the neck laterally, or to raise the 1st rib. Nerves, 



branches from the lower cervical. (See Fig. 38.) 

 Scalenus Medius, 22 from the upper surface of the 1st rib, behind the sub- 



clavian groove, into the transverse processes of the lower 6 cervical 



vertebrse. Action, same as scalenus anticus. Nerves, branches from the 



lower cervical. 

 Scalenus Posti'cus, 21 from the outer surface of the 2d rib, into the posterior 



tubercles on the transverse processes of the lower 2 or 3 cervical vertebrae. 



Action, to flex the neck laterally, or to elevate the 2d rib. Nerves, branches 



from lower cervical. 



MUSCLES OF THE LARYNX AND EPIGLOTTIS. 



Crico-thyroid, from the front and side of the cricoid cartilage, into the lower 



and inner borders of the thyroid cartilage. Action, to elongate and make 



tense the vocal chords. Nerve, superior laryngeal. 

 Crico-arytenoideus Posticus, from the cricoid cartilage posteriorly, into the 



outer angle of the base of the arytenoid cartilage. Action, to rotate the 



arytenoid cartilages outwards and open the glottis, while keeping the vocal 



chords tense. Nerve, recurrent laryngeal. 

 Crico-arytenoideus Lateralis, from the upper border of the cricoid cartilage 



laterally, into the outer angle of the base of the arytenoid cartilage. 



Action, to rotate the arytenoid cartilages inwards and close the glottis. 



Nerve, recurrent laryngeal. 

 Thyro-arytenoideus,/n7* the receding angle of the thyroid cartilage and the 



crico-thyroid membrane, into the base and anterior surface of the arytenoid 



cartilage. Action, to shorten and relax the vocal chords by approximating 



the cartilages. Nerve, recurrent laryngeal. 

 Arytenoideus, from the posterior surface and outer border of one arytenoid 



cartilage, into the corresponding parts of the opposite cartilage, filling up 



the posterior concave surface of these cartilages. Action, by approximating 



the arytenoids, to close the back part of the glottis. Nerves, superior and 



recurrent laryngeal. 

 rhyro-epiglottideus, from the inner surface of the thyroid cartilage, into\\\e 



margin of the epiglottis and the aryteno-epiglottidean fold. Action, a de/ 



pressor of the epiglottis. Nerve, recurrent laryngeal. 



