IGS MYOLOGY. 



MASSETER. 



• {Zygomatico-niaxillaris. ) 



(Pl. II. 11. Fig. 70. h.) 



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. — Fi'om 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 ai-tery 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-inaxHlaris.) 

 (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 zygomatic 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. 



