72 IR 



PHYSIOLOGY OF THE NERVOUS SYSTEM. 



ference to the locomotive actions, and the great 

 developement of the vesicular nervous matter 

 in these regions betokens the frequent and 

 energetic evolution of the nervous force. All 

 the structural arrangements necessary for this 

 purpose are found in the antero-lateral columns. 

 The posterior columns come into exercise in 

 balancing the trunk and in harmonizing its 

 movements with those of the lower extre- 

 mities. 



Some support is obtained for this view of the 

 function of the posterior columns from the phe- 

 nomena of disease. In many cases, in which 

 the principal symptom has been a gradually in- 

 creasing difficulty of walking, the posterior 

 columns have been the seat of disease. Two 

 kinds of paralysis of motion may be noticed 

 in the lower extremities, the one consisting 

 simply in the impairment or loss of the 

 voluntary motion, the other distinguished by 

 a diminution or total loss of the power of co- 

 ordinating movements. In the latter form, 

 while considerable voluntary power remains, 

 the patient finds great difficulty in walking, and 

 his gait is so tottering and uncertain that his 

 centre of gravity is easily displaced. These 

 cases are generally of the most chronic kind, 

 and many of them go on from day to day with- 

 out any increase of the disease or improvement 

 of their condition. In two examples of this 

 variety of paralysis I ventured to predict dis- 

 ease of the posterior columns, the diagnosis 

 being founded upon the views of their func- 

 tions which I now advocate ; and this was 

 found to exist on a post-mortem inspection ; 

 and in looking through the accounts of re- 

 corded cases in which the posterior columns 

 were the seat of lesion, all seem to have com- 

 menced by evincing more or less disturbance 

 of the locomotive powers, sensation being af- 

 fected only when the morbid change of struc- 

 ture extended to and more or less involved the 

 posterior roots of the spinal nerves. 



Bellinger! put forward the opinion that the 

 anterior columns of the spinal cord influenced 

 movements of flexion, and the posterior co- 

 lumns those of extension; to the grey matter 

 he assigned the office of propagating sensitive 

 impressions to the brain ; and the lateral co- 

 lumns, according to him, exercised an influ- 

 ence upon the organic functions of nutrition 

 and circulation. 



The views already referred to respecting the 

 grey matter show that it cannot be regarded as 

 devoted exclusively to one function of the ner- 

 vous system ; nor can it be viewed as capable 

 of taking its part in nervous actions without 

 the white or fibrous matter. 



Valentin adduces some experiments not un- 

 favourable to the supposition that the nerves of 

 extensor muscles pass towards the posterior part 

 of the cord, and those of the flexor muscles to 

 the anterior part. He found that if, in frogs, 

 the posterior surface of the cord on one side of 

 the posterior median fissure in the region of the 

 second or third vertebra were irritated by the 

 point of a needle, the anterior upper extremity 

 of the same side was extended and drawn 

 backwards. When the anterior surface was 



irritated, the limb was drawn forwards to the 

 head. Irritation of the posterior column in 

 the region of the sixth vertebra and below it 

 caused extension of the posterior extremities, 

 but they were thrown into flexion by irritation 

 of the anterior columns. 



These are remarkable results; they need, 

 however, the confirmation of other observers. 

 If they be correct, the fact of the connection 

 of the nerves of extensor muscles with the 

 posterior columns has an interesting relation 

 with the supposed locomotive function, for 

 there can be no doubt that movements of ex- 

 tension contribute largely to the ordinary 

 attitudes and to the various modes of pro- 

 gression. 



Valentin refers to cases in which the anterior 

 columns having been the seat of tumor or of 

 softening, more or less permanent flexion of the 

 lower limbs had en-ued. These cases do not 

 favour his view unless he can show that the 

 lesion in all the cases was of the irritant kind, 

 inducing a spasmodic contraction of the flexor 

 muscles; for if the lesion be of a paralysing 

 kind, the effect would be to paralyse the flexor 

 muscles and allow the extensors full sway. The 

 explanation of the flexed state of limbs in 

 cases of this kind is probably to be derived 

 from a chronic state of contraction induced 

 in the muscles themselves by the lesion of the 

 nervous centre, and the state of flexion is as- 

 sumed rather than extension in consequence of 

 the predominance of flexor muscles over ex- 

 tension. 



Sir Charles Bell's doctrine, which assigned 

 to that portion of the cord which is interme- 

 diate between the roots of the nerves, (his 

 middle column,) a special power over the move- 

 ments of respiration, has long ceased to gain 

 attention from physiologists. It wanted the 

 support of anatomy. The so-called middle 

 column had no denned limits, nor could it be 

 proved that any respiratory nerves were con- 

 nected with this region of the cord, excepting 

 a few fibres of the spinal accessory nerve. The 

 distinct anatomy of a respiratory system of 

 nerves existed only in the imagination of the 

 inventor of the doctrine. It could not be 

 shown by experiment that the so-called nerves 

 of respiration had any special respiratory func- 

 tion beyond that which they exercised as the 

 motor nerves of certain muscles. And among 

 the nerves which Sir C. Bell had classed toge- 

 ther as nerves of respiration, were some which 

 certainly had no necessary connection with that 

 function. Of these the portio dura and the glosso- 

 pharyngeal are examples. 



Influence of the spinal cord upon the organic 

 functions. The influence of the spinal cord 

 upon certain organic functions has engaged a 

 large share of the attention of experimental 

 physiologists. It has been said to have a very 

 direct control over the functions of circulation, 

 calorification, secretion, especially that of the 

 kidneys. 



If it can be shown that the organs concerned 

 in these functions receive several nerves from 

 the spinal cord, then we do not stand in need 

 of vivisections to indicate to us that the 



