266 Mr. J. S. R. Russell. On the Nerve Roots of 



tion in this connexion, is proved by the difficulties met with in ob- 

 taining differentiation in the case of the nerve roots which enter 

 into the formation of the lumbo-sacral plexus, where the distance' 

 between the points of exit of the nerve roots from the neural canal 

 and the point where they unite to form the plexus is not so great as 

 in the case of the cervico -dorsal roots and the brachial plexus, and 

 where, consequently, differentiation is not so easy to effect as in the 

 latter case. If further proof were needed in support of the fact, 

 which I have repeatedly convinced myself and others of, viz., that it 

 is possible to separate the fibres concerned with one simple move- 

 ment in a nerve root from those concerned with another simple move- 

 ment, nothing could be more convincing than the results which I 

 obtained with regard to the recurrent laryngeal nerve.* In this 

 small nerve I found that it was possible to separate those nerve fibres 

 concerned with abduction from those concerned with adduction of 

 the vocal cords ; so that electrical excitation of the one set of fibres 

 evoked the one movement, while excitation of the other set evoked 

 the other movement. If such differentiation be possible in a nerve 

 of such small size, how much the more likely is it that it should be 

 possible in a nerve root of so much greater proportions ; unless it is 

 argued that the structural arrangement of nerve fibres in a nerve 

 root differs from that met with in a nerve trunk. My own observa- 

 tions leave no doubt in my mind that the structural arrangement in 

 a nerve root is identical with that met with in a nerve trunk ; and 

 there is, besides, abundant proof of this from the observations of 

 others, f 



Such single simple movements bear an almost constant relation to 

 the nerve roots, the same movements being, as a rule, found in any 

 given root, and such movements always bear the same relation to the 

 spinal level, e.g., extension and flexion of the knee are represented 

 together in one root, while extension is represented alone in the root 

 immediately above this, and flexion is represented alone in the root 

 immediately below this. 



Each bundle of nerve fibres, representing a single simple move- 

 ment in a nerve root, remains distinct in its course to the muscle or 

 muscles producing such a movement, without inosculating with other 

 motor nerve fibres. Additional evidence in support of this statement 

 is supplied by the results obtained in the case of the recurrent laryn- 

 geal nerve, for in this nerve it was found possible to separate accu- 

 rately the abductor from the adductor fibres, and to trace them by 

 dissection to the abductor or adductor muscles of the larynx. And 

 when one set of nerve fibres was divided while the other was left 



* ' Boy. Soc. Proc.,' vol. 51, 1892. 

 t Cf. Herringham, Paterson, &c. 



