PKINCIPLES FOR ANALYSIS OF POSTURES. 179 



joints. In the nervous hand the wrist is weak, 

 the fingers show irritability. 



IV. Consider the relative condition of posture in 

 collateral joints. 



The knuckles are collateral joints. The posture 

 of each may be similar, as in " the hand in rest/' or 

 it may be dissimilar, as in " the straight hand with 

 the thumb drooped," where the metacarpal bones, 

 which are collateral parts, are four in the same 

 plane, and that of the thumb is adducted. Col- 

 lateral differentiation is usually seen in the move- 

 ments of the hand in chorea, also in the spon- 

 taneous movements of the fingers of a healthy 

 infant ; it is marked in some cases of athetosis. 



V. Consider if the posture is symmetrical. Ob- 

 serve whether the postures of the corresponding 

 parts on the two halves of the body be sym- 

 metrical, whether the posture of either hand be 

 the same. Much has been said about this in 

 describing postures of the head and face. Perfect 

 symmetry indicates that the two halves of the 

 brain are acting similarly. 



VI. Consider if there be any indications of excite- 

 ment or over-action of any nerve-centre or centres 

 usually weak, such as the centre or nerve-mechanism 

 governing the extensor movement of a joint. 



Observations, comparisons, and analysis seem to 

 indicate the nerve-centre, or mechanism governing 

 the extension of a joint (i.e. the action of the weaker 

 muscles), as being weaker than the centre govern- 

 ing flexion. Observe if such indications of excite- 

 ment subside in sleep, or when at rest ; they do so 



