MYOLOGY 87 



Constrictor Glottidis. Location. — Supero-anterior portion of the 

 superior larynx. 



Origin. — From the superior and longitudinal line of the thyroid 

 plate. 



Insertion. — ^AU 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 lar5mx. 



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

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



Thyreo-aiytenoideus. 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. — ^AU 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-tracheaUs posticus and 

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

 about i3^ centimeters from the bifurcation of the trachea. 



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

 trachea, near the superior lar)ajx. 



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. 21, 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. 



