THE NASAL REGION. 399 



The Pyramidalis nasi is a small pyramidal slip prolonged downward from the 

 Occipito-frontalis upon the side of the nose, where it becomes tendinous and 

 blends with the Compressor nasi. As the two muscles descend they diverge, 

 leaving an angular interval between them. 



Relations. By its upper surface, with the skin ; by its under surface, with the 

 frontal and nasal bones. 



The Levator labii superioris alaeque nasi is a thin triangular muscle placed 

 by the side of the nose, and extending between the inner margin of the orbit and 

 upper lip. It arises by a pointed extremity from the upper part of the nasal 

 process of the superior maxillary bone, and, passing obliquely downward and 

 outward, divides into two slips, one of which is inserted into the cartilage of the 

 ala of the nose ; the other is prolonged into the upper lip, becoming blended with 

 the Orbicularis oris and Levator labii superioris proprius. 



Relations. In front, with the integument, and with a small part of the 

 Orbicularis palpebrarum above. 



The Dilatator naris posterior is a small muscle which is placed partly beneath 

 the elevator of the nose and lip. It arises from the margin of the nasal notch of 

 the superior maxilla and from the sesamoid cartilages, and is inserted into the 

 skin near the margin of the nostril. 



The Dilatator naris anterior is a thin delicate fasciculus passing from the 

 cartilage of the ala of the nose to the integument near its margin. This muscle is 

 situated in front of the preceding. 



The Compressor nasi is a small, thin, triangular muscle arising by its apex 

 from the superior maxillary bone, above and a little external to the incisive fossa ; 

 its fibres proceed upward and inward, expanding into a thin aponeurosis which 

 is attached to the fibro-cartilage of the nose and is continuous on the bridge of 

 the nose with that of the muscle of the opposite side and with the aponeurosis of 

 the Pyramidalis nasi. 



The Compressor narium minor is a small muscle attached by one end to the alar 

 cartilage, and by the other to the integument at the end of the nose. 



The Depressor alae nasi is a short radiated muscle arising from the incisive 

 fossa of the superior maxilla ; its fibres ascend to be inserted into the septum and 

 back part of the ala of the nose. This muscle lies between the mucous membrane 

 and muscular structure of the lip. 



Nerves. All the muscles of this group are supplied by the facial nerve. 



Actions. The Pyramidalis nasi draws down the inner angle of the eyebrows 

 and produces transverse wrinkles over the bridge of the nose ; by some anatomists 

 it is also considered as an elevator of the ala, and, consequently, a dilator _>f the 

 nose. 1 The Levator labii superioris alaeque nasi draws upward the upper lip and 

 ala of the nose : its most important action is upon the nose, which it dilates to a 

 considerable extent. The action of this muscle produces a marked influence over 

 the countenance, and it is the principal agent in the expression of contempt and 

 disdain. The two Dilatatores nasi enlarge the aperture of the nose. Their action 

 in ordinary breathing is to resist the tendency of the nostrils to close from 

 atmospheric pressure, but in difficult breathing they may be noticed to be in 

 violent action, as well as in some emotions, as anger. The Depressor alae nasi is 

 a direct antagonist of the other muscles of the nose, drawing the ala of the 

 nose downward, and thereby constricting the aperture of the nares. The Com- 

 pressor nasi depresses the cartilaginous part of the nose and compresses the alae 

 together. 



1 Although this muscle anatomically seems to be a continuation of the Occipito-frontalis down- 

 ward, it is really the reverse. Its origin is from the nose below, and its insertion into the Occipito- 

 frontalis and skin. If one pole of a battery be placed in front of the lobe of the ear, and the other 

 (a small pointed one) be carried up and down over the nose and forehead in the middle line, it is easy 

 to find a nodal point of indifference above which the Occipito-frontal draws the parts upward, and 

 below which the Pyramidalis draws them downward ( W. W. Keen, M. D., American edition). 



