Chap, it.] Phyfiogriomy. 147 



though this is partly to be attributed to the wafting of 

 the fat, which in youth fills the interftices between the 

 mufcles, and prevents ftrong lines. To the -above prin- 

 ciple is to be attributed the greater expreflionobfervablc 

 in the countenance of a perfon of a cultivated mind y 

 than in that of a perfon whofe flock of ideas is limited. 

 From all thefe circumftances it appears, that the culti- 

 vation of the mind is the moft likely method of iti- 

 creafmg the expreffion and beauty of the countenance. 



The mufcles of the lower jaw are four pairs, and are 

 thofe employed in the maftication of the food. 



The temporalis mufcle has a very extenfive origin^ 

 from the lower and lateral part of the parietal bone, all 

 the pars fquamofa of the temporal bone, from the ex- 

 ternal angular procefs of the os frontis, and from the 

 temporal procefs of the fphenoid bone. From thefe 

 different origins the fibres defcend like radii towards the 

 jugurti, under which they pafs, and are inferted into 

 the coronoid procefs of the lower jaw. Its ufe is to 

 prefs the lower jaw againft the upper, and at the fame 

 time to draw it a little backwards. This mufcle is 

 covered with a broad te,ndon, called its aponeurofis* 

 which defends it, and gives origin to a great number 

 bf mufcular fibres. 



The mafTeter arifes from the Superior maxillary bone, 

 where it joins the os malse, and from the inferior ajid 

 anterior part of the jugum, and is inferted into the angle 

 bf the lower jaw, which, when it a6bj it prefies againft 

 the upper. 



The pterygoideus internus proceeds from the inner 

 and upper part of the internal plate of the pterygoid 

 proceis of the fphenoid bone, and from the pterygoid 

 procefs of the 6s palati. It is inferted into the angle 

 of the lower jaw internally ^ and, when it ads, draws 

 it upwards and obliquely towards the pppofite fide. 



L2 the 



