1 82 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 264. — The deepest layer of the facial muscles and the temporalis. 

 The caninus, the zygomatic arch, a portion of the zygomatic bone with the origin of the masseter and the temporal 

 fasciae have been removed. 



Fig. 265. — The two pterygoidei seen from the inner surface. 

 The anterior portion of the skull has been divided in the sagittal plane, and the temporal bone in an oblique plane; 

 the tongue and soft palate have been removed. 



anterior border of the muscle is superficial, passing into the orbicularis oris and the other 

 muscles of the mouth. It is the strongest muscle in the oral region. 



It arises from the buccinator ridge of the mandible, from the posterior extremity of the alveo- 

 lar process of the maxilla, and from the pterygomandibular raphe. The pterygomandibular 

 raphe (pterygomaxillary ligament) is embedded in the buccopharyngeal fascia (see page 184) and 

 extends from the hamulus of the internal pterygoid plate to the posterior border of the alveolar 

 portion of the mandible. It separates the buc.mator from the constrictor pharyngis superior 

 (see "Splanchnology"). At the angles of the mouth the fibers of the buccinator muscles are directly 

 continuous with those of the orbicularis oris, while the posterior surfaces border immediately upon 

 the oral mucous membrane. The anterior portion of each muscle is covered by the risorius, the 

 triangularis, the zygomaticus, and the caninus, while the posterior portion is situated beneath 

 the masseter (see page 183), from which it is separated by a mass of fat, the buccal fat mass 

 (Bichat's fat mass). 



The buccinator is perforated by the parotid duct, and the small buccal glands rest 

 directly upon the muscle. 



THE NASAL MUSCLES. 



The muscles of the nose are much less important than those of the mouth. The feebly 

 developed nasalis (Figs. 262, 264, and 266) is composed of a transverse portion and an alar por- 

 tion. The transverse portion is a flat and very thin muscle which arises from the upper jaw and 

 is adherent to the angular head of the quadratus labii superioris upon the bridge of the nose; it 

 is united with its fellow of the opposite side by means of a thin aponeurosis termed the compressor 

 narium. The alar portion comes from the alveolar jugum of the upper canine tooth and goes to 

 the cartilage of the ala of the nose; its greater portion is covered by the quadratus labii superi- 

 oris, although a small portion is also concealed by the orbicularis oris. The ala of the nose 

 also receives constantly the insertion of a portion of the angular head of the quadratus labii 

 superioris. 



All of the muscles of the face proper are supplied by the facial nerve. Their function is to produce the movements 

 of expression, closure of the mouth, movements of the lips, and compression of the contents of the mouth (as, in blowing, 

 the buccinator). 



THE MUSCLES OF MASTICATION. 



The muscles of mastication are composed of four strong separate muscles which are divided 

 into two groups: the first group is formed by the masseter and the temporalis; the second by the 

 two pterygoidei. 



The masseter (Fig. 262) is a thick, strong, and approximately quadrilateral muscle which 



