70 APPLIED ANATOMY. 



inferior surface forward. This displacement is so marked that an excessive amount 

 of callus is thrown out and ankylosis may result. This so seriously interferes 



FIG 82. Fracture of the jaw, showing the action of the internal pterygoid and mylohyqid muscles in producing 

 displacement when the line of fracture runs from the outside forward and inward. 



with the use of the jaws as to justify an operation to remove or replace the upper 

 fragment in proper position. The injury is liable to be overlooked in children, and 

 as they grow up the deformity shown in Fig. 83 develops. 



FIG. 83. Deformity of the face following ankylosis due to fracture of the neck of the lower jaw in infancy (from an 



original sketch). 



Treatment. The lower jaw is held up in place by a bandage, and the upper 

 teeth act as a splint. Sometimes the teeth or fragments are wired in position, or an 

 interdental splint of gutta percha or other material is used. 



