480 SIR CHARLES BELL ON THE BRAIN. 



have been believed that the posterior roots of the spinal nerves were the same, in 

 function, with the anterior roots. When, however, it is understood that the anterior 

 column of the medulla oblongata gives off only filaments of motion, the rationale of 

 decussating fibres fails, or rather is imperfect ; for in injury of the brain, both motion 

 and sensation are lost on the opposite side of the body. We perceive how important 

 it was, in order to understand this symptom, that the posterior or sensitive part of 

 this column should be shown to descend from the cerebrum, and decussate at a point, 

 corresponding to that at which the decussation of the pyramidal bodies takes place. 



I have observed, that the corpus striatum is the part in which most frequently rup- 

 ture of the cerebral vessels occurs ; and the observations of authors correspond with 

 this opinion. In such cases we can readily believe that the power of motion will be 

 most injured ; whilst such derangement in the hemisphere must, at the same time, 

 more or less affect the sensibility. 



Certain circumstances essential to the study of the pathology of the brain are ex- 

 plained through this part of anatomy ; first, that motion and sensation should, in by 

 far the greater number of cases, be lost together, in disease of the brain ; because the 

 sensorial extremities of both columns are in the hemisphere of the cerebrum ; secondly, 

 it is seen why it is that the sensibility, as well as the power of motion, is injured on 

 the opposite side of the body when the hemisphere of the cerebrum is hurt or dis- 

 eased, for both columns decussate ; in the third place, the anatomy of the origin or 

 root of the fifth nerve explains very satisfactorily why, in palsy, the privation of sen- 

 sibility of the side of the face corresponds with that of the body. 



My paper should perhaps have terminated here, with these demonstrable facts, but 

 I am tempted to reach a little further. 



Further examination of the relation between the Brain and Spinal Marrow. 



Other questions will be suggested in reference to the symptoms of disease in the 

 brain. When the side of the body is paralytic, how far are the nerves affected which 

 appear to have their origin above the decussations ? Does the ninth or lingual, or the 

 portio dura of the seventh nerve, correspond with the spinal nerves ? Do the third 

 nerve and the muscles of the eye partake of the condition of the body ? 



As there is no decussation above the apparent origin of these nerves, and as the 

 commissures of the brain do not serve to explain this phenomenon, we are directed 

 in our inquiries to the spinal marrow. 



The spinal marrow has much resemblance to the brain, in the composition of its 

 cineritious and medullary matter, and in the union of its parts. In short, its structure 

 declares it to be more than a nerve, that is, to possess properties independently of the 

 brain. Another consideration presses upon us. Where are the many relations existing 

 between the different parts of the frame, and necessary to their combined actions, 

 established ? There must be a relation between the four quarters of an animal. If the 

 muscles of the arm or of the lower extremities are combined through the plexus of 



