THE BONES— FRACTURES 89 



The Supra-Orbital Process. — This is a solid rod of bone which 

 projects outwardly from the body of the frontal bone. It is convex 

 and roughened superiorly and concave and smooth inferiorly, where 

 it forms part of the roof of the orbit. Outwardly it is articulated to 

 the zygomatic process of the squamous temporal bone. Near its 

 root it is pierced by the supra-orbital foramen for the passage of the 

 supra-orbital artery, etc. 



The superior surface of the rod is immediately subcutaneous, and 

 it forms a prominent projection in the living animal. Above the 

 process is the temporal muscle. 



Although the process is in an exposed position and forms one of the 

 prominent parts of the body, it is not commonly fractured owing to its 

 thickness and strength. Fracture of this bone only occurs in animals 

 exposed to special risk, such as colliery ponies. When such a fracture 

 occurs and the bone is displaced downwardly, it exerts pressure upon the 

 eyeball, which must be relieved by raising the depressed piece of bone. 

 This is effected by making an incision through the skin over tlie 

 temporal muscle, behind the process. Through this incision a stout 

 metal probe is introduced, and passed immediately beliind the edge of 

 the process. The probe should rest on the zygomatic process of 

 the squamous temporal bone, and utilising the zygoma as the fulcrum, 

 the depressed bone is elevated by a process of leverage. 



The Inferior Maxilla. — This is made up of a body and two rami. The 

 body is placed anteriorly, and from it the rami diverge. It possesses two 

 surfaces, the inferior of which is convex and smooth, and in the living 

 subject is related to the lower lip. The upper surface is depressed and 

 smooth, and forms that part of the floor of the mouth upon which the 

 tip of the tongue rests. These two surfaces are separated from one 

 another by an edge which carries six alveoli for the incisor teeth. A 

 short distance behind the alveolus for the corner incisor on each side 

 is an alveolus for the canine tooth, which as a rule is only present in 

 the male. 



