166 MYOLOGY. 



DILATATOR. NARIS TRANSVERSALIS. 

 {Naso transverscdis.) 



Situated at the supero-anterior extremity of the nose, in front 

 of the nostrils, it is single, flat, and four-sided, consisting of 

 transverse fibres which cross each other. 



Origin. — The nasal peak. 



Insertion. — The superior surface of the cartilaginous alae of 

 the nostrils. 



Action. — ^It dilates the nostrils. 



DILATATOR NARIS INFERIORIS. 

 (Fig. 70. m.) 

 {Nasalis Brevis Ldbii Superioris — JSupermaxillo-nasalis Brevis.) 



Another long and four-sided muscle, situated at the side of, 

 and a little behind the nostrils. 



Origin. — -It arises by an aponeurotic origin from the upper 

 free margin of the superior maxilla and premaxilla. 



Insertion. — The skin of the false nostril. 



Action, — It dilates the nostril. 



DILATATOR NARIS SUPERIORIS. 

 (Fig. 70. n.) 



Situated just above the preceding, it is broad and thin, with 

 aponeurotic attachments. 



Origin. — From the lateral surface of the free margin of the 

 nasal bone. 



Insertion. — The skin of the false nostril. 



Action. — To assist the preceding muscle. 



DEPRESSOR LABII SUPERIORIS. 



ISituated on the inner surface of the upper lip, covered by 

 mucous membrane, it is thin and fleshy. 



Origin. — From the premaxilla at the alveoli, extending from 

 the lateral incisors to the tushes. 



Insertion. — The diverging fibres pass obliquely forwards to 

 blend with the upper lip and nasal cartilages. 



