THE MUSCLES. 129 



159. 2. Compressor narium s. transversus nasi. 



Figure : below, narrow (fleshy), above, broad, three-sided (ten- 

 dinous). Position : arched upon the cartilaginous part of the nose, 

 where both meet together. Origin : between the roots of the 

 canine and first molar teeth, in the sulcus naso-labialis. Inser- 

 tion : the back of the nose below the bony portion. Action: 

 rather to compress the nose, drawing the skin downwards, and 

 widening the nasal openings. 



Nerves: infraorbital. and elhmoidalis. 



160. 3. Dilatator narium posterior. 



Fig.: small. Pos.: at the posterior part of the alse nasi, covered 

 by depressor and compressor. Or.: the border of the proc. ascend. 

 of the upper jaw. Ins.: below to the skin of the posterior half 

 of the nasal openings. Act. : widens behind the nasal openings. 



161. 4. Dilatator narium anterior. 



Pos.: on the alae close to the back of the nose. Or. : the supe- 

 rior border of the alar cartilages of the nose. Ins. : the skin of 

 the anterior part of the border of the nasal openings. Act. : 

 draws the anterior portion of the alae nasi outwards. 



Nerves : infraorbital and facialis. 



Remarks. The rest of the nasal muscles are not independent, but continu- 

 ations of neighboring muscles; viz. 



a. Procems (s. pyramidalis) a continuation of frontalis, upon the dorsum of 

 the nose. Act. : draws the skin of the back of the nose upwards, stretching it. 



b. Depressor septi mobilis a portion of sphincter oris, in the fossa of the upper 

 lip. Act: draws the point of the nose upwards; contracting the nasal 

 openings. 



c. Pyramidalis s. Levator labii superioris akequi nasi. 



E. Muscles of the Lips, the Cheeks, and the Chin. 



162. 1. Orbicularis s. sphincter oris, the muscle closing 



the mouth. 



Pos.: round about the oral fissure in the lips, between the 

 mucous membrane and the external skin ; connected on the ex- 

 ternal circumference with the rest of the labial muscles (whose 

 continuation it forms). Or. and Ins.: septum mobile nasi. Act. : 

 closes, points, and presses the lips against the teeth (m. osculato- 

 nws). 



Nerves: infraorbit., mental, buciinat., facial. 

 9 



