MYOLOGY 89 



Origin. The anterior branch of the bifurcated tracheo-lateralis. 



Insertion. To the anterior extremity of the third half ring of the 

 bronchus of the same side. 



Shape. A small fasciculus. 



Relations. Internally with the trachea, and externally with the 

 skin and other integument. 



Action. A tensor of the inferior larynx. 



Broncho-trachealis Brevis (Fig. 20, No. 3). Location. Posterior 

 part of the inferior extremity of the trachea. 



Origin. From just beneath the broncho-trachealis anticus muscle. 



Insertion. Extends obliquely across the inferior larynx and is 

 inserted to the posterior end of the second bronchial ring. 



Shape. Rather short, strong, straight, subcylindrical. 



'Relations. Internally with the trachea, and laterally with the 

 broncho-trachealis posticus. 



Action. A tensor of the inferior larynx. 



Bronchialis Posticus (Fig. 21, No. 2). Location. Supero-lateral 

 side of the anterior end of the bronchi. 



Origin. From the lateral inferior margin of the last tracheal ring. 



Insertion. Passing obliquely across the larynx it inserts to the 

 posterior extremity of the second half ring of the bronchus. 



Shape. Small, thick, spindle-shaped. 



Relations. Internally with the trachea, inferiorly with the bron- 

 chialis anticus, and superiorly with the broncho-trachealis brevis. 



Action. A tensor of the larynx. 



Bronchialis Anticus (Fig. 21, No. i). Location. Inferior to the 

 former muscle. 



Origin. From the last ring of the trachea. 



Insertion. The fibers pass obliquely forward and become in- 

 serted to the rim of the arytenoid cartilage of the inferior larynx, 

 and the anterior extremities of the first and second half rings of 

 the bronchus. 



Shape. Thick, spindle-shaped; about twice the size of the bron- 

 chialis posticus. 



Relations. It is crossed at its origin by the broncho-trachealis 

 anticus and is related internally with the bronchus and end of the 

 trachea. 



Action. -A tensor of the larynx. 



Sterno-trachealis (Fig. 20, No. i). Location. The inferior re- 

 gion of the trachea above the above-named muscles.] 



