54 EQUINE ANATOMY. 



INTERNAL PTERYGOID. 



Origin. Palatine crest and pterygoid process. 

 Insertion. In hollow of maxillary ramus. 

 Action. Elevates and moves jaw laterally. 

 Nerve. Inferior maxillary of fifth. 



DIGASTRIC. 



Origin. Posterior belly from styloid process of occipital bone; 

 tendon passes through fibrous ring of insertion of stylo-hyoideus 

 into hyoid. 



Insertion. Into posterior border and internal face of inferior 

 maxilla. 



Action. Raises hyoid bone or depresses lower jaw. 



Nerve. Facial. 



MYLOHYOID. 



Origin. Mylo-hyoid ridge of inferior maxilla. 

 Insertion. Body of hyoid and anterior appendix and median 

 raphe between two muscles. 



Action. Same as above and also elevates tongue. 

 Nerve. Inferior maxillary of fifth. 



GENIO-HYOID. 



Origin. Genial surface of inferior maxilla. 

 Insertion. Extremity of hyoideal appendix. 

 Action. Draws hyoid forward and upward. 

 Nerve. Hypoglossal. 



STYLO-HYOID. 



Origin. Superior angle of styloid bone. 



Insertion. Base of hyoideal cornua. 



Action. Antagonizes former; carries hyoid up and back. 



Nerve. Facial. 



KERATO-HYOID. 



Origin. Posterior border of styloid cornu and inferior ex- 

 tremity of hyoid bone. 



Insertion. Superior border of thyroid cornua. 

 Action. Approximates two cornua. 

 Nerve. Hypoglossal. 



