THE HEAD, ANTERIOR. 67 



Masseter. Figs. 2, 3, 4. 



Origin. The deep portion, from the inner surface of the 

 zygomatic arch and from the posterior third of the lower 

 border of the same ; the superficial portion, from the lower 

 border of the anterior two-thirds of the zygomatic arch 

 and malar bone. 



Insertion. The deep portion, into the upper half of the 

 ramus of the lower jaw and coronoid process ; the super- 

 ficial portion, into the lower half of the ramus extending 

 as far as the angle. 



Nerve Supply. The inferior maxillary branch of the 

 fifth cranial nerve through its masseteric branch. 



Action. To close the jaw ; and, by the superficial por- 

 tion, to slightly protract it. 



Buccinator. Figs. 3, 4. 



Origin. From the pterygomaxillary ligament (a liga- 

 ment extending from the hamular process of the internal 

 plate of the pterygoid bone to the posterior extremity of 

 the mylohyoid ridge of the inferior maxilla) and from the 

 outer surface of the alveolar process of the superior and 

 inferior maxillary bones opposite the molar teeth. 



Insertion. Into the orbicularis oris, some of the lower 

 fibres passing into the upper lip, and some of the upper 

 fibres into the lower lip. 



Nerve Supply. The seventh cranial nerve through its 

 buccal branch. The buccal branch of the inferior maxil- 

 lary nerve passes to the muscle also. See page 1 1 j. 



Action. To retract the angles of the mouth, to flatten 

 the cheeks, and expel the contents of the mouth, also to 

 force the food between the teeth. 



