THE BONES— FRACTURES 91 



The coronoid process is plate-like, being flattened from side to side, 

 and its summit is rounded. It extends to a level of about one and a half 

 to two inches above the condyle, and in the living animal is deeply 

 seated to the zygomatic process of the squamous temporal bone. 



The condyle presents an articular surface superiorly, w^hich enters 

 into the formation of the temporo-maxillary joint. Just below this 

 surface it gives attachment outwardly to the external lateral ligament of 

 the joint, and inwardly to the external pterygoid muscle. 



The inferior extremity of the ramus is constricted and is attached 

 to the body. 



The inferior maxillary bone ossifies from two centres, one for each 

 ramus and the corresponding half of the body. The two halves of the 

 bone remain distinct along the median suture for about three months 

 after birth. 



The inferior maxilla is very commonly fractured. Frequently the 

 fracture is along the line fusion of the originally separate halves. 

 Another common seat is across the constricted portion of the ramus 

 just behind its attachment to the body. Pieces of bone may be 

 splintered off the subcutaneous portion of the horizontal ramus (the 

 vertical portion being protected by the masseter muscle), or the 

 angle of the jaw, whilst the walls of the molar alveoli are com- 

 monly broken. Injury to, and occasionally a small fracture of, the 

 inferior sharp edge of the horizontal portion is sometimes caused 

 by the violent use of a curb. 



Treatment of course varies with the seat and nature of the 

 fracture. As usual, any splintered pieces should be removed. 



When the fracture is along the symphysis the bones should be 

 replaced and maintained in position by means of wire twisted round 

 both halves of the body and passed in between the incisor teeth, 

 as in the treatment of similar fractures of the upper jaw. 



Fracture through the constricted portion of the ramus, when 

 unilateral, may be similarly treated, and co-aptation in this case is 



