723E 



PHYSIOLOGY OF THE NERVOUS SYSTEM. 



as regards the posterior pillars of the fornix, a 

 direct ratio to each other. 



Lallemand relates a case in which the symp- 

 toms were altogether limited to mental distur- 

 bance, without any affection of the sensitive or 

 motor powers, and the fornix and corpus callo- 

 sum were found in a state of complete softening 

 without discolouration. , 



The fibres of the pons Varolii bring the 

 cerebellar hemispheres into connection with 

 each other, and with the vesicular matter of 

 the mesocephale. Direct experiments on these 

 fibres can yield no satisfactory result, because 

 they are so intimately associated with the deep- 

 er seated parts of the mesocephale, and with 

 the nerves of the fifth pair and others, that it is 

 impossible to irritate them in the living animal 

 without affecting these parts likewise. The 

 anatomy of the fibres, however, sufficiently in- 

 dicates that they belong properly to a double 

 cerebellum : for when the cerebellum becomes 

 single, as in birds, reptiles, and fishes, no such 

 fibres are found in the encephalon. Morbid 

 lesion of the pons is productive of very serious 

 results from the number and importance of the 

 parts in its neighbourhood, the pyramids, the 

 medulla oblongata, the quaclrigeminal tuber- 

 cles ; so that the symptoms it produces cannot 

 be referred solely to the injury to the commis- 

 sural fibres. It is very probable, however, that 

 the crossed effect of deep-seated disease of 

 either hemisphere of the cerebellum may be 

 accounted for by the influence of these com- 

 missural fibres upon the adjacent anterior py- 

 ramids, which again would influence the oppo- 

 site side of the spinal cord. 



Having thus brought to a termination our 

 review of the physiology of the encephalon, I 

 may now sum up the principal conclusions 

 which our examination of this difficult and im- 

 portant subject leads to ; and these are embraced 

 in the following propositions. 



1. That the encephalon consists of a series 

 of centres, each of which has its proper influ- 

 ence in the exercise of the mental and bodily 

 functions. These are the centre of intellectual 

 actions, the centre of volition, the centre of 

 sensation, the centre of the coordination of 

 muscular movements, the centre of emotion, 

 and the centre of respiration and of deglutition. 



2. That the cerebral convolutions, with the 

 fibres which connect them to the corpora striata 

 and optic thalami, constitute the centre of intel- 

 lectual action. 



3. That the centre of volition consists prima- 

 rily of the corpora striata ; the inferior layers of 

 the crura cerebri, which are continuous with the 

 anterior pyramids, connect these gangliform bo- 

 dies with the vesicular matter of the crura (locus 

 niger), with the vesicular matter of the mesoce- 

 phale, medulla oblongata, and with that of the 

 spinal cord (the anterior horns), all of which with 

 the corpora striata probably form the dynamic 

 nervous matter in the impulses of volition for 

 nerves implanted in them respectively. 



4. The optic thalami, Which by the extension 

 of the olivary columns through the mesocephale 



and medulla oblongata to the posterior horns 

 of the vesicular matter of the spinal cord, 

 become continuous with those parts, constitute 

 the centre of sensation, having implanted in it 

 or connected with it less directly all the sentient 

 nerves of the body. 



The nerves of the higher senses probably 

 have each special, ganglia or centres, which, 

 however, are connected with the general centre ; 

 as the olfactory lobes for smell ; the retina, 

 corpora geniculata, or corpora quadrigemina 

 for vision ; the vesicular matter in which the 

 auditory nerves are implanted or the flocks 

 of Reil for hearing ; the ganglia of the fifth, 

 glosso-pharyngeal, and posterior roots of spinal 

 nerves for taste and touch. 



5. The cerebellum constitutes the centre of 

 the coordination of muscular movements, both 

 in locomotion and in all the complicated move- 

 ments of the frame. 



6. The upper and posterior part of the me- 

 socephale, including probably the greatest por- 

 tion of the corpora quadrigemina, constitutes 

 a special centre of actions referable to the emo- 

 tions, among which may be reckoned sexual 

 impulses. This centre connects itself with the 

 medulla oblongata by the olivary columns, and 

 through the same channel with the posterior 

 horns of the spinal vesicular matter. 



7. The medulla oblongata constitutes the 

 centre of respiration and deglutition, but it 

 cannot be considered as wholly devoted to 

 these functions, inasmuch as it consists like- 

 wise of continuations of the centres of volition, 

 of sensation, and of emotion.* 



Of the functions of the ganglions. That 

 ganglions are small nervous centres we are 

 bound to believe, from the existence in them of 

 a considerable quantity of vesicular matter min- 

 gled with fibrous matter. And the views which 

 we have already expressed respecting the dy- 

 namic character of the vesicular matter warrant 

 the assumption that wherever a special accumu- 

 lation of that form of nervous matter is found, 

 there must be a special source of nervous 

 power. 



* I have great pleasure in referring the reader to 

 a very able essay on the physiology of the brain, 

 (which I did not see until this article was at press,) 

 in which very similar views to those expressed in 

 the text are advocated, based on comparative ana- 

 tomy. The author, who injustice to himself ought 

 not to withhold his name, is evidently hampered 

 by his adhesion to the excito-motory doctrines. I 

 allude to the Review of Noble on the Brain in 

 Dr. Forbes's Journal for October, 1846. I had 

 already put forward similar opinions respecting the 

 subdivision of the brain and the uses of its parts, 

 in the section headed " An hypothesis of the action 

 of the brain," in the article NERVOUS CENTRES, pub- 

 lished in 1845, and subsequently republished in a 

 volume entitled "The physiological and descrip- 

 tive Anatomy of the Brain, &c." chap. xii.,andthe 

 same views were expressed in Mr. Bowman's and 

 my " Physiological Anatomy and Physiology of 

 Man," part ii. 1845, p. 291 and p. 374. I may add 

 that the review to which I refer contains a very 

 complete and masterly exposition of the weakness 

 of the present system of phrenology. 



