g6 SURGICAL APPLIED ANATOMY. [Chap. vn. 



the masseter, int. pterygoid, and temporal. It must 

 be remembered that the mylo-hyoid muscle will be 

 attached to both fragments, and will modify the 

 amount of displacement. Fractures of the ramus 

 are seldom attended with much displacement, muscular 

 tissue being nearly equally attached to both fragments. 



In fractures of the body of the bone, the dental 

 nerve often marvellously escapes injury, a fact that is 

 explained by the supposition that the bones are not 

 usually sufficiently displaced to tear across the nerve. 

 Weeks after the accident, however, the nerve has 

 become so compressed by the developing callus as to 

 have its function destroyed. 



One, or both, condyles have often been broken by 

 falls or blows upon the chin. 



The gums being firm and adherent, it follows 

 that they are usually torn in fractures of the body of 

 the maxilla, and hence the bulk of the fractures in 

 this part are compound. 



The temporo- maxillary articulation is 

 supported by a capsule which varies greatly in thick- 

 ness in different parts. By far the thickest part of 

 the capsule is the external part (the external lateral 

 ligament). The internal part is next in thickness, 

 while the anterior and posterior portions of the 

 capsule are thin, especially the former, which is very 

 thin. Thus, when this joint suppurates, the pus is 

 least likely to escape on the external aspect of the 

 Articulation, and is most likely to find an exit through 

 the anterior part of the capsule, although this part is 

 to a great extent projected by the attachments of the 

 external pterygoid muscle. ^ Immediately behind the 

 condyle of the jaw are the bony meatus, and, a little to 

 the inner side, the middle ear. In violent blows upon 

 the front of the jaw, these structures may be damaged, 

 and it is interesting to note that the strongest liga- 

 ment of the joint (the external lateral) has a direction 



