Mr. C. S. Sherrington. 



[Mar. 17, 



Eoot. Movement. 



rator internus, quad. fern, and the two 

 gemelli. 



9th Subthoracic . . Short flexor of the digit and hallux, adductor 

 of the hallux, interossei and lumbricalers, 

 sphincter vaginae, obturator internus, sphinc - 

 ter ani. 



The results of the experiments are in harmony with those of 

 Eckhardt. Many of the muscles of the limb are supplied by thre e 

 spinal roots, some by two ; one alone, as far as I have yet observed, 

 l)y a single root only. Individual variation is frequent. Excitation 

 of the same spinal root not always throws into action the same 

 muscles, even in individuals of the same species, sex, and approximate 

 age ; nor does it always produce the same movement, e.g., flexion at 

 knee followed excitation of 5th root in two individual instances. 

 Analysis of the distribution of the component filaments of a root 

 shows that in different individuals filaments which correspond in 

 absolute position in the nerve-root do not correspond in function. 

 Nevertheless, Herringham's " Law I " (quoted above) holds good for 

 the outflow of fibres throughout considerable regions of the cord, 

 although a sciatic plexus of the post-axial class may occur in the 

 same individual as a brachial plexus of the pr,e-axial class, so that in 

 its narrowest sense the "law" is not always applicable to great 

 lengths of the cord. No exception has been found to it in the sense 

 that an efferent fibre pre-axial in one individual to some particular 

 other efferent fibre is ever in any individual of the same species post- 

 axial to it. 



The distribution of the peripheral nerve-trunks is not obviously 

 different, whether by its root- formation the plexus belong to the pre- 

 axial or to the post-axial class. The peripheral nerve-trunks are, as 

 regards their muscles, relatively stable in comparison with the spinal 

 roots. When the innervation of the limb-muscles is of the pre-axial 

 -class, so also is that of the anus, vagina, and bladder ; and conversely. 



The region of outflow from the spinal cord of the fibres destined for 

 a natural group of the limb- muscles, or the representation of a par- 

 ticular movement at a limb joint, is often not conterminous with the 

 origin of the filaments of a spinal root, but has its limits at points 

 within spinal segments, either overstepping or falling short of their 

 boundaries. Thus the outflow to the intrinsic muscles of the sole 

 sometimes has its upper limit placed nearly midway up the region of 

 •origin of the filaments of the 6th root. The lower limit of the out- 

 flow to the calf muscles sometimes lies about two-thirds down the 

 region of origin of the 8th root. Other examples could be cited. 

 The ankle, knee, &c, which seem to be divisions between funda- 



