250 
SIR CHARLES BELL ON THE NERVOUS SYSTEM. 
Let us be distinct. There are two anterior or motor columns in the spinal marrow ; 
and two, more posteriorly situated, sensitive columns. These resemble each other 
in this, that they respectively interchange filaments, the anterior columns with each 
other, and the posterior columns with each other. 
No other columns of the spinal marrow make this interchange ; and the respiratory 
columns are far apart. 
It is not unnatural to conclude that such interchange is necessary to the infinite 
varieties in the associated actions of the frame, where sensation and voluntary mo- 
tion are in operation ; whilst the uniformity of the respiratory act requires no such 
provision. At all events, the respiratory nerves arise from columns which do not de- 
cussate, a circumstance which distinguishes the systems. 
It was an early object with me, to make out the connexion between the roots of 
the diaphragmatic nerve and of the spinal accessory nerve. I conceived that as these 
nerves were closely united in office, the latter elevating the shoulders, so as to assist 
in the due expansion of the chest, while the former excites the diaphragm* — for the 
expansion of the chest is necessary to the full action of the diaphragm — they might 
have the same origin. But independently of anatomical investigation, and waiting 
for those occurrences in practice which are perhaps better than experiment, symptoms 
seem to confirm the correctness of this view. 
In the case already alluded to, of disease in the bodies of the cervical vertebrae, 
and which I have selected from among others, merely because at the time of writing 
it is a subject of daily inspection, the common muscular motions of the neck and 
arms are entirely suspended, whilst the breathing is not, and never has been affected. 
The arms hang like empty sleeves, the head falls forward, if not supported with 
the hand or by an instrument, the muscles are wasted, and the neck thin ; yet in 
breathing, the mastoid muscle and the trapezius muscle swell and become as firm as 
a piece of board. 
Anatomical investigation shows the roots of the spinal accessory nerve arising far 
apart from the muscular roots of the nerves of the arms : indeed they are more nearly 
allied to the roots of sensation than of motion ; and in the instance above, we find 
common muscular actions cut off, and those of respiration perfect. We see the sen- 
sibility in the whole extent of the respiratory passages, and the influence of the will 
retained, through the respiratory nerves. The same phenomena are presented in the 
common case of hemiplegia. 
Such facts countenance the view which was presented to the Society, where a pe- 
culiar office was ascribed to these nerves, and a distinct name given to them. 
But there remain some questions of great difficulty and much interest. And I am 
now happy in taking the assistance of the experiments made by various ingenious 
gentlemen. 
* Some have supposed that the diaphragm expands the chest laterally ; an effect which I cannot conceive 
possible. 
