858 CENTRAL NERVOUS SYSTEM 



ascribing sensations to definite parts of the body, which in fact are 

 hallucinations arising from some functional disorder of the brain which 

 is affecting directly the sensory centers of the cortex. 



Referred Pain. The accuracy of sensory location seems to be corre- 

 lated with the abundance of sense organs in different parts of the body 

 and with the frequency of their employment. On the hands, the lips, 

 and tongue localization is extremely accurate, for these organs are in 

 frequent use in examining the nature and position of various objects. 

 Localization is good on the soles of the feet, which are used to sound 

 out the ground in walking. On the other parts of the limbs, the trunk, 

 and particularly the back, stimuli can be localized only in a rather rough 

 way. Particularly interesting is the phenomena of localization of sen- 

 sations arising from the viscera. In healthy life these organs do not 

 give rise to sensory manifestations, but in disease of the viscera acute 

 pains may be set up. Because visceral sensations arise from organs 

 within our body, we have no way of knowing just where the trouble 

 lies and consequently have no basis for localizing the disturbance accu- 

 rately. In the case of stationary organs such as the heart, the pain 

 may be referred at times to the proper internal region, but in the case 

 of movable organs such as the intestine, the reference is most inexact. 



DISTRIBUTION OF REFERRED PAIN FROM VISCERAL ORGANS (AFTER POTTENGER) 



The eight cervical segments are indicated by Cl, C2-C8; the twelve dorsal or thoracic 

 segments by Dl, D2-D12; the five lumbar segments by LI, L2-L5; and the four sacral 

 segments by Sac. 1, Sac. 2, Sac. 4. The areas of the head are indicated as follows: 

 N nasal or rostral area; FN f ronto-nasal area ; MO medio-orbitalarea; FT fronto- 

 temporal area; T temporal area; V vertical area; P prietal area ; O occipital area ; 

 NL naso-labial area; Max/ maxillary area; Man. mandibular area; M mental area; 

 L. S. Superior laryngeal area; LI inferior laryngeal area; TO hyoid area. 



