MOVEMENTS OF THE HUMAN FACE. 195 



general form and outline of a face is largely 

 determined by the shape of the skull beneath. 

 There is probably more direct expression seen in 

 the face than in any other part of the body. The 

 face is an index of the brain : the mobile conditions 

 of the face are so many direct expressions of the 

 brain condition ; especially are those fine shades of 

 variation expressive which accompany emotions 

 and mentation. 



We also see in the face many examples of expres- 

 sion by uniform coincident development ; * this is an 

 empirical form of expression, in which the condition 

 of development of the parts we can see indicates 

 the probable state of the brain which we cannot 

 see. These different modes of expression must be 

 considered separately. 



In studying such a difficult and complex subject 

 as the direct expression of the face, certain methods 

 must be followed, and the different facial expressions 

 that have been observed must be analyzed and 

 described. The principal movements of the facial 

 muscles are : 



1. Dilatation and contraction of the facial 

 foramina the openings of the eyes, nose, and 

 mouth. 



2. Elevation and depression of parts, as the eye- 

 brows, the angles of the mouth, etc. 



3. Retraction and drawing forward of parts, as in 

 grinning and screwing up the mouth, corrugation 

 of the forehead. 



Either side of the face can move separately; 



* See chap, xviii. 



