LIGAMENTS AND MUSCLES OF THE HORSE. 35 



Insertion. — To the external surface of the ramus of the inferior 



maxilla. 

 Action.— To raise the lower jaw, thus bringing the teeth 



strongly together. 

 Temporalis. 



Origin. — Yvom the temporal fossa. 



Insertion. -To the coronoid process of the inferior maxilla. 

 Action.— Chiefly to elevate the lower jaw ; or to oppose pro- 

 trusion action of the external pterygoid. Also to cause 



lateral motion. 

 Pterygoideus Internus. 

 Origin.— From a rough crest formed by the palatine bone and 



the pterygoid process of the sphenoid. 

 Insertion.— To the excavated internal sui-face of the ramus of 



the inferior maxilla, 

 ^c^zon.— Together, they elevate the lower jaw ; singly, produce 



lateral movement. 



PTERYCiOIDEUS ExTERNUS. 



Oricjhi.—YYom the wing and pterygoid pi-ocess of the sphenoid. 

 Insertion.— To the neck below the condyle of the inferior 



maxilla. 

 Action.— A.cth\^ together, they protrude the lower jaw ; acting 



singly, the lower jaw is carried to the side opposite to the 



muscle acting. 



DiGASTRICUS. 



Oriyin.—¥vom the styloid process of the occipital, in common 

 with the stylo-maxillaris. 



Insertion.— 'i'o the ramus of the inferior maxilla, near the sym- 

 physis. 



Action.— To depress the lower jaw, and open the mouth. 



Stylo-maxillaris. 



Origin.— Fvom the styloid process of the occipital bone. 

 Insertion.— To the angle of the inferior maxilla. 

 Aciion.-To depress the lower jaw and open the mouth. 



