EXAMINATION OF SOME SPINAL NERVES 127 
followed by flexion of digits. Extension of elbow replacing the more usual flexion of 
elbow is very unusual from this root. 
Vlth Cervical Root. — Flexion of elbow ; adduction and flexion of thumb, less frequently with 
flexion of the other digits ; drawing back of shoulder, but less marked. 
Vth Cervical Root. — Flexion of elbow ; movement of shoulder, sometimes retraction, sometimes 
a drawing up ; adduction and flexion of thumb, less frequently of other digits as well. 
Retraction of shoulder, when it occurs, is not so well marked as at lower root ; it is 
sometimes a simple adduction toward spinal column. 
IVth Cervical Root. — Retraction of shoulder, or else protraction and lifting of shoulder ; flexion 
of elbow ; not invariable, occasionally flexion and adduction of thumb with or with- 
out flexion of other digits; lateral flexion of neck. 
Ilird Cervical Root. — Elevation of shoulder ; drawing down of same side of head ; flexion of 
elbow feeble and occasional. The flexion of elbow from this and preceding roots 
was always, in great measure, supinator longus action. Twisting of head and neck to 
opposite side. 
Ilnd Cervical Root. — Drawing up of shoulder, down of head on same side ; turning of chin 
toward opposite shoulder with neck. Neither in this root nor in preceding did 
moderate stimuli evoke contraction in the muscles of the hyoid region. 
Vth Cranial Nerve. — Opening of mouth ; turning of chin toward opposite shoulder ; wrinkling 
of muzzle ; conjunctival reflex. 
The above results possess points of interest, but it must not be forgotten the value of a 
reflex obtained by exciting the afferent spinal root, or one of its filaments, is but slight as regards 
the light thrown by it on the normal working of the spinal cord. It is only truly estimated 
when it is remembered that the Mammalian spinal root is not a functional combination but a 
morphological one.* To stimulate the whole of one single afferent root by itself is to do what 
in Nature never normally occurs. So also to stimulate one continuous half or fourth of such 
a root, is to do what is never done naturally. The end of a penholder pressed upon the skin 
anywhere — at least, anywhere on the limbs — excites contemporaneously single nerve fibres 
scattered through two consecutive (in many cases three consecutive) spinal afferent roots. 
Experiments on the roots are suitable at the commencement of an investigation of the spinal 
reflex action, because the roots, more readily than the peripheral nerves, provoke reflexes {vide 
infra\ and the experiments are, therefore, easier to perform ; but they are less valuable in their 
physiological results, because the accompanying conditions are less known and less controlled. 
The root reflexes, to be of use for the understanding of the working of the cord, must be 
considered in collation with peripheral nerve reflexes and with skin-spot reflexes. For that reason 
I shall not consider them alone here, but later with the other reflexes obtained. 
Spinal Shock. 
Here it is necessary not to forget the possibility — indeed, certainty — that by cutting out 
* Sherrington, ' Journ. of Physiol.,' vol. 13, 1892. 
