192 PHYSICAL EXPRESSION. 



suggested for defining the postures and movements 

 of the head, and the movements and combinations 

 of movement possible to the head are explained. 

 It is shown that flexion and extension are the only 

 symmetrical movements of the head. 



The action of light and the sight of objects in 

 causing head rotation present interesting examples 

 of expression, and some of the varying conditions 

 of mentation are expressed by variations in such 

 movements under the same stimulus on different 

 occasions. 



Head rotation is a sign of negation. Semiflexion 

 of the head with rotation and inclination to the same 

 side indicates weakness ; this is often seen when the 

 free left hand is in the nervous posture, the rotation 

 and inclination then being to the right. 



Gravity exerts a marked influence upon the 

 postures of the head, especially in weakness and in 

 sleep. The head is usually free, and therefore 

 expressive of brain conditions. 



The principle of the contrast of the action of 

 small parts with larger parts, is illustrated by 

 comparing the head movements with those of the 

 face and eyes. Extension of the head and hands 

 occurs coincidentally in astonishment. 



Movements of the lower jaw depend upon two 

 pairs of brain nerves. Depression of the jaw is 

 spasmodic in yawning ; it may be due to gravity. 



Certain forms of the head are indicative of defects 

 of brain, and are commonly seen in idiots. 





