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M. Temporalis. 



This is small and fan-shaped, and arises from the whole 

 inner surface of the posterior part of the orbital foramen. 

 It is inserted into the coronoid process of the lower max- 

 illary bone. The front margin of this muscle may be seen 

 through the orbital foramen, just back of the eye. The 

 insertion at that part of the jaw, which corresponds to the 

 coronoid process, is directly above that of the most super- 

 ficial slip of the Myloglossus. The length of the muscle 

 is about 10 . Its function is similar to that of the Tem- 

 poralis in human anatomy. 



M. Masseter. 



The Masseter is a small muscle of almost quadrangular 

 shape, with a muscular origin and insertion. Its anterior 

 margin is slightly shorter than its posterior, which lies 

 directly under the curved tube of the ear (meatus audi- 

 torius externus) and the distal portion of the Sterno- 

 mastoideus. The muscle arises from what corresponds 

 to the lower edge of a zygomatic process. This origin 

 begins about half an inch in advance of the anterior edge 

 of the orbital foramen, and extends directly backward 

 for about an inch. It is inserted into a curved line cor- 

 responding with a sigmoid notch, extending from the 

 coronoid process to the angle of the jaw. The length of 

 the insertion is about the same as' the length of the ori- 

 gin- 

 There are two Pte'rygoid muscles, which are well 



marked, corresponding with the Pterygoideus Extemus 

 and Pterygoideus Internus. 



M. Pterygoideus Externus. 

 The Pterygoideus Externus is a larger muscle than 



