THE SUPERIOR MAXILLARY REGION. 307 



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. 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 aud 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 Avell as in some 

 emotions, as anger. The Depressor alse nasi is a direct antagonist of the other 

 muscles of the nose, drawing the ala of the nose downward, and thereby constrict- 

 ing the aperture of the nares. The Compressor nasi depresses the cartilaginous 

 part of the nose and compresses the alse together. 



6. Superior Maxillary Region (Fig. 195). 



Levator labii superioris. Zygomaticus major. 



Levator anguli oris. Zygomaticus minor. 



The Levator labii superioris (proprius) is a thin muscle of a quadrilateral form. 

 It arises from the lower margin of the orbit immediately above the infraorbital 

 foramen, some of its fibres being attached to the superior maxilla, others to the 

 malar bone ; its fibres converge to be inserted into the muscular substance of the 

 upper lip. 



Relations. By its superficial surface above, w y ith the lower segment of the 

 Orbicularis palpebrarum ; below, it is subcutaneous. By its deep surface it 

 conceals the origin of the Compressor nasi and Levator anguli oris muscles, 

 and the infraorbital vessels and nerve, as they escape from the infraorbital 

 foramen. 



The Levator anguli oris arises from the canine fossa immediately below the 

 infraorbital foramen ; its fibres incline downward and a little outward, to be 

 inserted into the angle of the mouth, intermingling with those of the Zygomaticus 

 major, the Depressor anguli oris, and the Orbicularis. 



Relations. By its superficial surface, with the Levator labii superioris and 

 the infraorbital vessels and nerves ; by its deep surface, with the superior maxilla, 

 the Buccinator, and the mucous membrane. 



The Zygomaticus major is a slender fasciculus which arises from the malar 

 bone, in front of the zygomatic suture, and, descending obliquely downward and 

 inward, is inserted into the angle of the mouth, w T here it blends with the fibres of 

 the Levator anguli oris, the Orbicularis oris, and the Depressor anguli oris. 



Relations. By its superficial surface, with the subcutaneous adipose tissue; 

 by its deep surface, with the Masseter and Buccinator muscles and the facial artery 

 and vein. 



The Zygomaticus minor arises from the malar bone immediately behind the 

 maxillary suture, and, passing downward and inward, is continuous with the 

 Orbicularis oris at the outer margin of the Levator labii superioris. It lies in 

 front of the preceding. 



Relations. By its superficial surface, with the integument and the Orbicularis 

 palpebrarum above ; by its deep surface, Avith the Masseter, Buccinator, and 

 Levator anguli oris, and the facial artery and vein. 



Nerves. This group of muscles is supplied b,y the facial nerve. 



Actions. The Levator labii superioris is the proper elevator of the upper lip, 

 carrying it at the same time a little forward. It assists in forming the naso-labial 

 ridge, which passes from the side of the nose to the upper lip and gives to the face 

 an expression of sadness. The Levator anguli oris raises the angle of the mouth, 



