NERVE-MUSCULAR POSTURES. 169 



A posture observed can only be considered as the 

 outcome of the spontaneous action of the nerve- 

 mechanism when the limb or part is free and dis- 

 engaged. If the muscles of the hand are engaged 

 in holding an object, or in an act of manipulation, 

 the postures of the hand are not simply the out- 

 come of the spontaneous action of the nerve- 

 mechanism. 



Postures are frequently seen accompanying, and 

 apparently caused by, demonstrable brain-disease ; 

 as examples, the " convulsive hand," cerebral facial 

 palsy.* When these postures occur otherwise, 

 apparently spontaneously, they may be looked 

 upon as nerve-muscular signs produced by the 

 nerve-mechanism corresponding. 



Postures which are frequently seen in very young 

 children and infants are certainly spontaneous. 

 Postures seen to be frequently repeated in many 

 such young subjects are probably spontaneous 

 nerve-muscular actions. With regard to postures 

 thus observed in many infants, it is probable that 

 the piece of nerve-mechanism corresponding is well 

 developed, and rendered very definite so as to be 

 easily excited to spontaneous action. 



When a posture seen in an adult is found to 

 be analogous to one often seen in infants, the 

 probability of its spontaneous origin is strength- 

 ened. 



Postures of disengaged parts, still observed in 

 man, and frequently represented in ancient art,f 



* See pp. 108, 109, Figs. 10, 11. 

 f See Fig. 35, p. 300. 



