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. Caries, 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-sarcoma, 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 or fibro-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 jiingous growths of va rious kinds also attack the bones of the face. A few cases of hydatids (the aceplialo-cystus) have been met with in the upper jaw.