272 MUSCLES OF TEE HEAD AND NECK. 



The zygomaticus minor, a very small mnscle, arises from the an- 

 terior and inferior part of the malar bone, and inclines downwards and 

 forwards to terminate by joining the outer margin of the levator labii 

 superioris; sometimes near the origin of that mnscle. It lies internal 

 to the zygomaticus major, but distinct from it in its whole length. 



The zygomaticus major, placed externally to the smaller mnscle of 

 the same name, arises from the malnr bone near the zygomatic suture, 

 from which it descends to the angle of the mouth, where it is continued 

 into the orbicularis and depressor anguli oris. 



Yarktic.-^. — The zygomaticus minor is frequently absent ; or it may fall 

 short of the mouth, and be inserted into the fascia of the cheek. It may arise 

 wholly or in part from the orbicularis palpebraram ; it has also been obsei*ved 

 joined to the zygomaticus major, or to the levator labii superioris, or even to the 

 outer fibres of the frontalis (Eustachius). It has frequently Ijeen found double. 



The zygomaticiis major has also been found double, or it may be double merely 

 at its origin. Sometimes it arises from the masseteric fascia below the zygoma. 

 (Macalister.) 



Tlio risorixis, or smiling muscle (Santorini), is generally regarded as 

 a part of the platysma myoides. It consists of some very thin fasciculi, 

 which commence in the fascia over the masseter, or on the parotid 

 gland, and, extending transversely inwards in the fat of the check, 

 join the orbicularis and depressor anguli oris at the angle of the 

 mouth. 



yarlrth'n. — The risorius has been scon to arise from the integument over the 

 upper end of the stemo-mastoid (Hallet) ; from the zygoma (McAMiinnie) ; from 

 the external ear (Albinus) ; and from the fascia over the mastoid process (Mac- 

 alister). It was found double and even triple by Santorini. 



The lower and lateral part of the face receives a superficial muscular 

 covering from the facial part of t'hc platysma myoides, which is in- 

 corporated with the muscles of the angle of the mouth and lower lip, 

 and passes along with the superficial iascia over the base of the jaw 

 into the cervical portion of the muscle ; while the anterior portion of 

 the cervical platysma, continuous externally with the facial, takes firm 

 attachment to the base of the jaw for a length of two inches or more 

 external to the symphysis. 



The buccinator muscle consists of a flat and thin but strong set of 

 fibres in contact with the mucous membrane, and forming a consider- 

 able part of the wall of the mouth. It is attached by its upper and 

 lower margins to the outer surface of the alveolar parts of the maxillary 

 bones, opposite the molar teeth, and by its posterior margin to the 

 ■pterijijo-maxillary ligament, a narrow band of tendinous fibres, which 

 extends from the internal pterygoid plate to the mylohyoid ridge of the 

 lower jaw close to the last molar tooth, and is placed between the 

 buccinator muscle and the superior constrictor of the pharynx. From 

 these points the fibres of the muscle are directed forwards, approaching 

 each other, so that the muscle is narrowed and proportionally thickened 

 near the angle of the mouth, where it becomes incorporated with the 

 orbicularis. The fibres near the middle of the muscle cross each other, 

 those from above passing into the lower lip, and those from below into 

 the upper one ; but the higher and lower fibres are du'ected into the 

 corresponding lip without decussation. 



Jhintions. — The buccinator is covered and supported by a thin fascia, which 

 IS closely adherent to the muscular fibres ; and is overlapped by the triang-uian.s 



