482 THE NERVOUS SYSTEM. 



connected with the brain still excites sensations which are 

 felt as if derived from the parts to which the peripheral 

 extremities of the nerve-fibres are distributed. Thus, 

 there are cases of paralysis in which the limbs are totally 

 insensible to external stimuli, yet are the seat of most 

 violent pain, resulting apparently from irritation of the 

 sound part of the trunk of the nerve still in connection 

 with the brain, or from irritation of those parts of the 

 nervous centre from which the sensitive nerve or nerves 

 supplying the paralysed limbs originate. 



An illustration of the same law is also afforded by the 

 cases in which division of a nerve for the cure of neuralgic 

 pain is found useless, and in which the pain continues or 

 returns, though portions of the nerve be removed. In 

 such cases, the disease is probably seated nearer the nervous 

 centre than the part at which the division of the nerve is 

 made, or it may be in the nervous centre itself. When the 

 cause of the neuralgia is seated in the trunk of the nerve 

 for example, of the facial or infra-orbital nerve division 

 of the branches can be of no service ; for the stump remain- 

 ing in connection with the brain, and containing all the 

 fibres distributed in the branches of the nerve to the skin, 

 continues to give rise, when irritated, to the same sensa- 

 tions as are felt when the peripheral parts themselves are 

 affected. Division of a nerve prevents the possibility of 

 external impressions on the cutaneous extremities of its 

 fibres being felt ; for these impressions can no longer be 

 communicated to the brain : but the same sensations which 

 were before produced by external impressions may arise 

 from internal causes. In the same way may be explained 

 the fact, that when part of a limb has been removed by 

 amputation, the remaining portions of the nerves which 

 ramified in it may give rise to sensations which the mind 

 refers to the lost part. When the stump and the divided 

 nerves are inflamed, or pressed, the patient complains of 

 pain felt as if in the part which has been removed. When 

 the stump is healed, the sensations which we are accus- 



