118 ANNALS NEW YORK ACADEMY OF SCIENCES 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC OROUP 

 {INNERVATED BY VII) 



Digastricus (pars posterior). — The digastric as a whole is a large 

 muscle arising on the mastoid and inserted on the lower edge of the 

 mandible^, posterior to the symphysis. 



FELIS 



The cat furnishes a good example of a specialized carnivorous jaw 

 with chiefly orthal or vertical movement. 



MUSCLES OF THE ADDUCTOR OR TEMPORAL GROUP 

 (INNERVATED BY V^) 



Masseter Pterygoideus internus 



Temporalis Digastricus (pars anterior) 



Pterygoideus externus 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 (INNERVATED BY VII) 



Digastricus (pars posterior) 



MUSCLES OF THE ADDUCTOR OR TEMPORAL GROUP 

 (INNERVATED BY V^) 



Masseter. — This has three layers in the cat, but it has about the same 

 insertion and origin as in man. 



Temporalis. — This is more extended than in man, reaching to the 

 parietal crest. Its insertion is on the outer side of the coronoid process. 



Pterygoideus externus. — Arises in the external pterygoid fossa between 

 the foramen rotundum and the spheno-palatine foramen. Its insertion 

 is on the inner side of the coronoid process. The coronoid process is very 

 high and the condyle very low, so that the muscle has changed its inser- 

 tion. 



Pterygoideus internum. — Arises in the pterygoid fossa in about the 

 same position as in man. The insertion is on the inner border of the 

 mandible and extends back to the angle. Its fibers on the inner side go 

 to the masseter, and it is partly united with the pterygoideus externus 

 and the stylo-hyoid ligament. 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 (INNERVATED BY VII) 



Digastricus (pars posterior). — The digastric as a whole arises on the 

 mastoid and occipital bones. Inserted on the lower edge of the mandible, 

 just anterior to the first premolar. It is entirely inside of the jaw. 



