384 



MYOLOGY 



The Buccinator (Fig. 380) is a thin quadrilateral muscle, occupying the interval 

 between the maxilla and the mandible at the side of the face. It arises from the 

 outer surfaces of the alveolar processes of the maxilla and mandible, corresponding 



to the three molar teeth; and behind, from 

 the anterior border of the pterygomandib- 

 ular raphe which separates it from the 

 Constrictor pharyngis superior. The fibers 

 converge toward the angle of the mouth, 

 where the central fibers intersect each 

 other, those from below being continuous 

 with the upper segment of the Orbicu- 

 laris oris, and those from above with the 

 lower segment; the upper and lower fibers 

 are continued forward into the corre- 

 sponding lip without decussation. 



BUCCINATOR 



FIG. 380. Muscles of the pharynx and cheek 



TRIANGULARJS 



Fio. 381. Scheme showing arrangement of fibers of 

 Orbicularis oris. 



Relations. The Buccinator is covered by the buccopharyngeal fascia, and is in relation by 

 its superficial surface, behind, with a large mass of fat, which separates it from the ramus of the 

 mandible, the Masseter, and a small portion of the Temporalis; this fat has been named the 

 suctorial pad, because it is supposed to assist in the act of sucking. The parotid duct pierces the 

 Buccinator opposite the second molar tooth of the maxilla. The deep surface is in relation with 

 the buccal glands and mucous membrane of the mouth. 



The pterygomandibular raphe (pterygomandibular ligament) is a tendinous band 

 of the buccopharyngeal fascia, attached by one extremity to the hamulus of the 

 medial pterygoid plate, and by the other to the posterior end of the mylohyoid 

 line of the mandible. Its medial surface is covered by the mucous membrane of 

 the mouth. Its lateral surface is separated from the ramus of the mandible by a 

 quantity of adipose tissue. Its posterior border gives attachment to the Constrictor 

 pharyngis superior; its anterior border, to part of the Buccinator (Fig. 380). 



The Orbicularis oris (Fig. 381) is not a simple sphincter muscle like the Orbic- 

 ularis oculi; it consists of numerous strata of muscular fibers surrounding the 

 orifice of the mouth but having different direction. It consists partly of fibers 

 derived from the other facial muscles which are inserted into the lips, and partly 

 of fibers proper to the lips. Of the former, a considerable number are derived from 

 the Buccinator and form the deeper stratum of the Orbicularis. Some of the 

 Buccinator fibers namely, those near the middle of the muscle decussate at 

 the angle of the mouth, those arising from the maxilla passing to the lower lip, 

 and those from the mandible to the upper lip. The uppermost and lowermost 

 fibers of the Buccinator pass across the lips from side to side without decussation. 

 Superficial to this stratum is a second, formed on either side by the Caninus and 



