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the voluntary muscles with the brain. 
We have noticed, that there is a plexus formed both on 
the nerves which convey the will to the muscles, and on the 
nerves which give the sense of the condition of the muscles. 
The reason of this I apprehend to be that the nerves must 
correspond with the muscles, and consequently with one 
another. If the motor nerve has to arrange the action of 
several muscles so as to produce a variety of motions, the 
combinations must be formed by the interchange of filaments 
among the nerves before they enter the muscles, as there is 
no connection between the muscles themselves. As the 
various combinations of the muscles have a relation with the 
motor nerves, the same relations must be established by 
those nerves which convey the impression of their combina- 
tions, and a similar plexus or interchange of filaments there- 
fore characterizes both. 
We have seen that the returning muscular nerves are 
associated with the nerves of sensibility to the skin, but they 
are probably very distinct in their endowments, since there 
is a great difference between conveying the sense of external 
impressions, and that of muscular action. 
In surgical operations the fact is forced upon our attention 
that the pain of cutting the skin is exquisite, compared with 
that of the muscles ; but we must remember that pain is a 
modification of the endowment of a nerve, serving as a guard 
to the surface, and to the deeper parts consequently. This 
has been some days separated from the brain, the muscle is excited as when the 
nerve was first divided. The property, however it may be defined, is therefore in 
the nerve. Our language might perhaps be made more precise if we used terms 
which implied the course of nervous influence, whether from or towards the brain ; 
but it will be difficult to express this without the aid of hypothesis. 
