168 MYOLOGY. 



MASSETER. 



(Zygomatico-maxillaris.) 

 (PL. II. 11. FIG. 70. k.) 



Situated on the posterior part of the cheek, of which it forms 

 the large fleshy portion, it is broad, thick, flat, and irregularly 

 four-sided, consisting of several layers, intersected by tendinous 

 bands, and enclosed in a strong aponeurosis. 



Origin. From the zygoma, the spine and external surface of 

 the superior maxilla. 



Insertion. The outer surface, posterior border, and angle of 

 the inferior maxilla. 



Relation. Externally with the facial panniculus. Over its 

 surface are distributed the facial nerves, and along its anterior 

 border lies the parotid duct, and the facial artery and vein ; 

 buried beneath its substance is the alveolar vein or vena varicosa. 



Action. To elevate the lower jaw and close the mouth, being 

 an important muscle in mastication. 



TEMPORALIS. 



(Temporo-maxillaris. ) 



(PLS. II. 3 ; III. 1.) 



Situated in the temporal fossa, which its fills, this muscle is 

 strong and fleshy, intersected by tendon, and covered by fascia. 



Origin. From the parietal ridge, and part of the occipital 

 crest, the z^gomatic process of the temporal and the external 

 surface of the parietal bones. 



Insertion. The coronoid process of the inferior maxilla. 



Relation. Externally with the muscles of the ear, and the 

 scutiform cartilage ; inferiorly with the pterygoid muscles. A 

 pad of fat lies between it and the orbital fossa. 



Action. With its fellow it assists in closing the mouth ; 

 singly it gives slight lateral motion to the lower jaw. 



STYLO-MAXILLARIS. 

 (PL. III. 1'.) 



Situated behind the lower jaw, it is pyramidal and fleshy. 

 Origin. From the styloid process of the occiput. 



