SIR CHARLES BELL ON THE BRAIN. 479 



direction towards its origin. For this purpose, with a small and fine knife, we cut 

 into the substance which surrounds the sensitive root, to the depth of a twelfth of an 

 inch, and then lay aside the knife and take the curette, and perhaps the ivoiy handle 

 of the knife *. With these we push aside the substance of the brain, in doing which 

 there is no difficulty in distinguishing the smooth, flat, and ribbon -like white nerve. 

 Continuing to press aside the matter of the pons, and, when separated, to cut it away, 

 we find the nerve taking a course backwards and downwards into the medulla oblon- 

 gata, making a considerable angle. Here we are interrupted by the crossing of the 

 portio mollis of the seventh nerve. We observe in passing, that the portio mollis has 

 two roots ; that besides that usually described passing round the processus ad cere- 

 bellum to the anterior part of the fourth ventricle, it has a round root, which enters 

 anteriorly to that process. But by attention and much neat dissection we may pre- 

 serve these roots of the seventh nerve, and, recovering the tract of the fifth nerve 

 below, trace it downwards. We are again interrupted by the origins of the eighth 

 pair of nerves ; and here, too, it will be found, on careful dissection, that this nerve 

 does not correspond with the*description in systematic works. But to proceed with 

 our proper subject. Some part of the root of the fifth may be seen to deviate in a 

 direction towards the calamus scriptorius ; but the main tract descends behind the 

 fasciculus of the corpus olivare, by the side of the great fasciculus of fibres which 

 we have already traced down from the cerebrum. Disregarding this association, 

 and following still the root of the fifth nerve, we find it continued to the roots of the 

 superior spinal nerves ; and in tracing it thus far, we must conclude that its rela- 

 tions are with the spinal marrow rather than directly with the brain, and that it 

 joins the posterior column below the decussation of that sensitive tract or co- 

 lumn. It remains a proper subject of inquiry to determine how far the deviation of 

 a part of the sensitive tract of this nerve corresponds with its complex function in 

 being the source of taste as well as of common sensibility. 



It has been observed by diligent anatomists from time to time, that the nerves of 

 the encephalon come off^ in a direction ascending from the spinal marrow. There 

 can be no doubt that the sensitive root of the fifth ascends, and that it has its origin 

 in the spinal marrow rather than in the brain. Without at present inquiring into 

 the minute anatomy of the other nerves, we may draw very important conclusions 

 from what is before us. 



It is rather surprising, that from what was known of the anatomy of the brain, 

 pathologists should have so agreed in their explanation of the phenomenon of injury 

 of one side of the brain producing its effects on the opposite side of the body. Their 

 opinion was founded on the decussation of the anterior columns, or pyramidal 

 bodies, and those only; but great misconception must have prevailed as to the ana- 

 tomy, when such an explanation could be satisfactory ; and, at all events, it must 



* If we order dissecting instruments, there is no end to the trouble of procuring them fine enough. The 

 operating case of the oculist, however, furnishes at once all that is necessary for delicate anatomy. 



3 q2 



