220 



FACE. 



which have been just mentioned, the develop- 

 ment of the two jaws is unequal, the corre- 

 spondence of their alveolar borders is lost, and 

 mastication becomes in proportion imperfect : 

 in mammiferous animals the unequal size of 

 the lower jaw, by preventing suckling, is often 

 a cause of death. The bones of the face are 

 much more symmetrical than those of the cra- 

 nium, and rarely present the disproportion in 

 their lateral development which is observed in 

 the latter. 



Under the head of defect or arrest of deve- 

 lopment may be noticed, 1. the occasional ab- 

 sence of some of the bones, as for example, the 

 lachrymal or the vomer; 2. the existence of 

 fissures, or non-union of the upper maxillary 

 bones, and, as a more rare case, the separation 

 of the two halves of the lower jaw. Fissures 

 of the upper jaw may exist in various degrees, 

 and may occur with or without a corresponding 

 cleft in the soft palate and lip ; it may appear 

 as a mere slit along the middle of the roof of 

 the mouth, forming a narrow communication 

 between that cavity and one side of the nose ; 

 or it may extend along the whole of the pala- 

 tine arch, and be continuous behind with a 

 similar division of the soft palate, without, at 

 the same time, being accompanied with hare- 

 lip. Sometimes the aperture is very wide, and 

 the palatine plates of the upper maxillary and 

 palate bones are almost entirely wanting; in 

 this case the vomer and middle cartilage of the 

 nose are also partially or entirely absent ; and 

 there is both hare-lip and cleft of the soft 

 palate, so that the mouth, both sides of the 

 nose, and the pharynx are laid into one great 

 cavity. When the fissure exists at the anterior 

 part of the palate only, it almost invariably 

 occurs at the suture which has been described 

 between the maxillary and intermaxillary bones, 

 so that the cleft separates the canine from the 

 lateral incisor tooth ; when the fissure occurs 

 on both sides of the face, the four incisor teeth 

 are separated from the others and lodged in an 

 alveolar border, which usually in this case 

 projects more or less towards the lip, in which 

 there is also commonly a single or double cleft 

 or hare-lip. Sometimes the fissure occurs in 

 the intermaxillary bone itself between the lateral 

 and middle incisor teeth, and then we find a 

 single incisor on one side and three on the op- 

 posite : it is very rarely that the cleft exists in 

 the median line between the two intermaxillary 

 bones. 



Among the arrests of development which 

 occur in the bones of the face may be enume- 

 rated a fissure which occasionally extends 

 across the lower border of the orbit, and a 

 suture which sometimes divides the os jugum 

 into two pieces. 



The union which not unfrequently takes 

 place between the bones of the upper jaw by 

 the obliteration of their sutures, is commonly 

 the effect of age, and usually occurs between 

 the bones of the nose, between the vomer and 

 sphenoid, and between the inferior turbinated 

 and upper maxillary bones. Wounds and frac- 

 tures of the bones of the face readily unite. 

 Those most subject to these injuries are such 



as are the most prominent, viz. those of the 

 nose, cheek, and lower jaw ; the last is the 

 most frequently broken. The alveolar pro- 

 cesses and the delicate bones in the orbit and 

 nose are also liable to injury. The bones of 

 the face are subject, like the rest, (though not 

 so commonly as those of the cranium,) to hy- 

 pertrophy and atrophy. Exostosis appears most 

 frequently on the upper jaw, in the orbit, or 

 along the alveolar border on the outer surface 

 of the bones ; on the lower jaw it is situated 

 usually along the alveolar border, at the angle 

 or on the body of the bone. Inflammation of 

 the periosteum and bones of the face occurs 

 spontaneously or as the result of injuries or 

 disease, and presents the usual phenomena. 

 Abscesses also take place either within the 

 cancellous structure of the more solid bones, 

 or in the cavities which they contain ; when 

 matter forms within the, antrum, it may be 

 evacuated by extracting the canine or the large 

 molar tooth, which often projects into this ca- 

 vity, and then piercing through the bottom of 

 their sockets. When necrosis affects the bones 

 of the face, its ravages are seldom repaired (as 

 in the case of cylindrical bones) by the pro- 

 duction of new osseous matter ; some attempts 

 at reparation after the separation of a seques- 

 trum have been, however, observed in the lower 

 jaw. Curies, either simple or connected with 

 syphilitic or strumous disease, may attack 

 nearly all the bones of the face, but it more 

 particularly affects the alveolar borders of the 

 jaws and the delicate bones about the nose and 

 palate; it is often attended with partial ne- 

 crosis. Caries of the face may occur as the re- 

 sult of malignant ulcerations, of lupus, or of the 

 various forms of cancer which affect the soft 

 parts. Both the upper and lower jaw are sub- 

 ject to osteo-sarcoina, commencing either on the 

 surface or in the interior of the bones, and ac- 

 quiring sometimes an enormous size, so as to 

 encroach on the orbit, nose, and mouth, and 

 materially to impede the motions of the lower 

 jaw. For these growths and others more sim- 

 ple, of a. fibrous orjibro-cartilaginous structure, 

 large portions (sometimes amounting to nearly 

 the whole) of the upper or lower jaw have been 

 removed with success. Cyst-like tumours, con- 

 taining a serous fluid, have been found in the 

 lower jaw. The more intractable diseases of 

 medullary sarcoma and./ungous growths of va- 

 rious kinds also attack the bones of the face. 

 A few cases of hydatids (the acephalo-cystus) 

 have been met with in the upper jaw. 



THE MUSCLES OF THE FACE 



are arranged around the orifices of the eyelids, 

 the nose, and the mouth, and may be divided 

 into constrictors and dilators of these apertures. 

 The nostrils, however, undergo but little vari- 

 ation in their dimensions, being maintained 

 permanently open by the elastic cartilages 

 which form them. The eyelids also contain 

 elastic cartilages, which are moulded upon 

 the front of the globe over which they glide in 

 obedience to the muscles which dilate or con- 

 tract the orifice between them. The mouth, 

 which is the most mobile of the facial aper- 



