MYOLOGY 87 



Constrictor Glottidis. Location. Supero-anterior portion of the 

 superior larynx. 



Origin. From the superior and longitudinal line of the thyroid 

 plate. 



Insertion. All along the inner margin of the arytenoid bone, and 

 to the apex of the mid-cricoidal segment. 



Shape. Thin, flat sheet extending outward and upward, and then 

 inward. 



Relation. Inferiorly with the larynx. 



Action. The two muscles of this kind acting together, close the 

 glottis by drawing the apices of the arytenoids to the median line. 



Thyreo-arytenoideus. Location. Supero-lateral portion of the 

 superior larynx. 



Origin. From the entire outer margin of the thyroid plate and 

 the outer margin of the cricoid bone. 



Insertion. All along the outer margin of the arytenoid bone and 

 the outer border of the central cricoid piece. 



Shape. A thin, flat sheet. 



Relations. Infero-laterally with the superior larynx. 



Action. The two muscles of this kind acting together, open 

 the glottis by pulling the arytenoid bone outward. 



Tracheo-lateralis (Fig. 20, No. 2). Location. Along the lateral 

 side of the trachea. 



Origin. By the union of the bronchio-trachealis posticus and 

 bronchio-trachealis anticus, on the lateral side of the trachea, 

 about 1^2 centimeters from the bifurcation of the trachea. 



Insertion. In delicate fan-like structure to the side of the 

 trachea, near the superior larynx. 



Shape. Thin, ribbon-shaped, closely attached to the trachea. 



Relations. Internally with the trachea, and externally with the 

 skin and other integument. 



Action. Acts as a brace to the sides of the trachea, and contract- 

 ing, approximates the tracheal rings and thus shortens the trachea. 



Broncho-trachealis Posticus (Fig. 2 1 , No. 3) . Location. Postero- 

 superior portion of the trachea. The fibers pass downward and 

 backward. 



Origin. From the inferior end of the tracheo-lateralis. 



Insertion. To the end of the third half of the bronchial ring of 

 the same side. 



Shape. A small fasciculus. 



