THE BUCCAL REGION 



375 



upper lip. Other fibres of the muscle, situated at its upper and lower part, 

 pass across the lips from side to side without decussation. Superficial to this 

 stratum is a second, formed by the Levator and Depressor anguli oris, which cross 

 each other at the angle of the mouth, those from the Depressor passing to the upper 

 lip, and those from the Levator to the lower lip, along which they run to be in- 

 serted into the skin near the median line. In addition to these there are fibres from 

 the other muscles inserted into the lips the Levator labii superioris, the Levator 

 labii superioris alaeque nasi, the Zygomatici, and the Depressor labii inferioris; 

 these intermingle with the transverse fibres above described, and have principally 

 an oblique direction. The proper fibres of the lips are oblique, and pass from the 

 under surface of the skin to the mucous membrane through the thickness of the 

 lip. In addition to these are fibres by which the muscle is connected directly 

 with the maxilla and mandible and with the septum of the nose. In the upper lip 

 these consist of two bands, an inner and an outer, on each side of the nasal plane; 

 the outer band (TO. incisivus superior] arises from the alveolar border of the maxilla, 

 opposite the lateral incisor tooth, and, arching outward on each side, is continuous 



ISORIUS 

 BUCCINATOR 



FIG. 294. Plan of the fibres constituting the Orbicularis oris muscle. 



at the angle of the mouth with the other muscles inserted into this part. The 

 inner band (TO. nasolabialis) connects the upper lip to the septum of the nose. 

 The interval between the two inner bands corresponds with the depression called 

 the philtrum seen on the surface of the skin beneath the septum of the nose. The 

 additional fibres for the lower lip (TO. incisivus inferior) arise from the mandible, 

 externally to the Levator menti, and arch outward to the angles of the mouth 

 to join the Buccinator and the other muscles attached to this part. 



The Buccinator (Fig. 295) is a broad, thin muscle, quadrilateral in form, 

 which occupies the interval between the jaws at the side of the face. It arises 

 from the outer surface of the alveolar processes of the maxilla and mandible, 

 corresponding to the three molar teeth, and, behind, from the anterior border of 

 the pterygomandibular ligament, which separates it from the Superior constrictor 

 of the pharynx. The fibres converge toward the angle of the mouth, where the 

 central fibres intersect each other, those from below being continuous with the 

 upper segment of the Orbicularis oris, and those from above with the inferior 

 segment; the highest and lowest fibres continue forward uninterruptedly into the 

 corresponding segment of the lip, without decussation. 



