248 



Muscles of the Head. 



Tuberculum articulare 



'SI. pterygoideus externus 



M. pterygoideus internus 



Kaiibe pterygoniandibularis 



Ductus parotideus (cut through) 



M. buccinator 



294. Mm. pterygoidei of the right side, external view. 



(The arcus zj'gomaticus has been removed as m Fig. 293 : the processus coronoideus and an 

 adjacent piece of bone have been chiselled out of the rannis mandibulae.) 



M. buccinator (see also Figs. 290, 291 and 293). Form: ilat, oblong-quadrangular, 

 thin. Posit i<Hi: beneath all the other muscles of the mouth like a transverse, curved band ; 

 close to the mucous membrane of the cheeks and lips, along the rows of teeth. Origin: rajihe 

 pt^^Tj'goraandibularis , lateral surface of the i)rocssus alveolaris maxillae and the crista bucci- 

 natoria (or corresponding portion) of the lower jaw bone. The fibres run partly parallel, 

 partly they decussate into the upper and lower lip at the angles of the mouth and there 

 go over into the fibres of the muscles of the other side. In the li])S it forms the deepest 

 layer of the m. orbicularis oris. Action: it draws the angle of tln' mouth lateralward, closes 

 the mouth opening, presses the lips and cheeks upon the teeth. Innervation: n. faciaUs. 



