FALLACIES AS TO MEANING OF POSTUKES. 171 



prone, but will fall into extension if the forearm is 

 held out supine. Dorsal decubitus results from 

 gravity, together with general palsy of the motor 

 nerve-mechanism. 



Postures may be due to local nerve injury or 

 disease, thus : injury to the facial nerve ; * injury to 

 the musculo-spiral nerve ; a gumma pressing upon 

 the third cranial nerve, may produce certain pos- 

 tures of the parts supplied by these nerves, such 

 postures not depending upon the condition of the 

 nerve-centres. 



Postures may be due to rigid muscular con- 

 traction dependent upon permanent brain lesion, 

 such as descending sclerosis. Such cases should be 

 kept separate from the postures due to a temporary, 

 it may be momentary, condition of the central 

 nerve-mechanism. It is hoped that some proofs 

 have been given that the study of spontaneous pos- 

 tures as indications of the condition of the brain is 

 useful, and that it may be considered as one of the 

 exact methods of studying the nervous system in 

 its physiological and pathological conditions. 



The subjoined tables contain descriptions of eight 

 typical postures, applying the " principles " to the 

 study of each. 



* See Fig. 27, p. 202, representing facial palsy. 



