SIR CHARLES BELL ON THE BRAIN. 473 



relations which exist between the parts of the brain, and the connexions of these with 

 the nerves distributed over the body. The advantage with which we now enter on this 

 inquiry is obvious, for instead of seeking, by injuring the substance of the brain, to 

 discover the effects on remote parts of the nervous system, we commence the inquiry 

 with a knowledge of that system. 



It being now universally allowed that nerves have distinct functions, and not a 

 common quality, and that the sensitive and motor roots of the nerves spring from 

 different sources, it must appear a very natural mode of inquiry to follow these nerves 

 into the brain, and to observe the tracts of nervous matter from which they take their 

 origin. It is surely an easy, as well as a natural proceeding, to follow these tracts, 

 and to mark the portions of the brain to which they ultimately tend ; finally, to 

 inquire what is the effect of the diseases of these parts, what the accompanying 

 symptoms, and to compare the symptoms with the anatomical details. 



On this plan I now propose to demonstrate that sensibility and motion belong to 

 the cerebrum, — that two columns descend from each hemisphere, — that one of these, 

 the anterior, gives origin to the anterior roots of the spinal nerves, and is dedicated 

 to voluntary motion, — and that the other (which from its internal position is less 

 known) gives origin to the posterior roots of the spinal nerves, and to the sensitive 

 root of the fifth nerve, and is the column for sensation. 



Further, I propose to show that the columns of motion which come from different 

 sides of the cerebrum join and decussate in the medulla oblongata, — that the columns 

 of sensation also join and decussate in the medulla oblongata. Finally, that these 

 anterior and posterior columns bear in every circumstance a very close resemblance 

 to one another, — that is to say, the sensorial expansions of both are widely extended in 

 the hemispheres : they pass through similar bodies towards the base of the brain, and 

 both concentrate and decussate in the same manner, thus agreeing in every respect, 

 except in the nervous filaments, to which they give origin. 



Of the striated Septa in the Medulla Oblongata and Pons Varolii. 



We can have no hesitation in giving superior importance to those tracts of striated 

 matter which descend from the brain to the spinal marrow, since they are obviously 

 the lines of communication between the organ of the mind and the frame of the body. 

 But these longitudinal tracts are separated by certain plates of fibrous matter which 

 go directly transverse, are very regular, very easily demonstrated, and although no 

 doubt important in themselves, are particularly useful to us in our present view, 

 as establishing the natural distinctions or boundaries between the columns which 

 descending from the encephalon constitute the medulla oblongata and the spinal 

 marrow. 



I shall first name parts that are familiar, as being noticed in systematic works, and 

 proceed to others which I conceive have been overlooked. Of the former class are 



