152 



Muscles of the Head. 



206, Muscles of the Lower Jaw (the Pterygoid 



Muscles), from inside. 



M. temporalt's, (Fig. 204). Orig. : From the whole of the tem- 

 poral fossa and from the inner surface of the temporal fascia. Insert. : 

 Below the zygomatic arch at the coronoid process of the lower jaw. 

 (Elevator and retractor of the lower jaw.) 



M. massctcr (Fig. 204) has two portions, superficial and deep. Orig. : 

 Zygomatic arch. Insert. : Outer surface of the ramus of the lower jaw as 

 far as the angle. (Elevates the lower jaw and draws it forwards.) 



J\I. pteryyoidc.ns interims. Orig. : Pterygoid fossa of the sphenoid bone. 

 Insert.: Lower half of the inner side of the ramus of the lower jaw. 

 (Elevates the lower jaw and draws it forwards and somewhat laterally.) 



M. pterygoideus cxternus. Orig.: Outer surface of the external ptery- 

 goid plate and great wing of the sphenoid bone, tuberosity of the superior 

 maxillary bone. Insert.: By a strong tendon at the neck of the condyle 

 of the lower jaw, at the inner wall of the capsule and of the inter- 

 articular fibro-cartilage of the temporo-maxillary articulation. (Acting on 

 both sides it draws the lower jaw forwards ; acting on one side it draws 

 it laterally.) 



