chap, iv.] SPINAL NERVES: MAN. 137 



last are sometimes supplied by the Vlth, sometimes by the Vllth, 

 but they are never in any case placed above the supinators. These 

 are always supplied by the Vlth alone. The flexor group in the 

 forearm show a similar fixed relation." Herringham concludes 

 that " the nerve roots are not always composed of the same fibres, 

 but that what is in one case the lower bundle of the Vth may be 

 in another the upper bundle of the Vlth, and what is now the 

 upper bundle of the VHIth will at another time be the lower of 

 the Vllth root." Hence the following principle is enuntiated : 

 " Any given fibre may alter its position relative to the vertebral 

 column, but ivill maintain its position relative to other fibres." 



Herringham, W. P., Proc. Boy. Soc, xll, 1886 pp. 423, 427, 

 430, 435. 



By physiological methods, Sherrington working chiefly on 

 Macacus, but on other animals also, found that this principle sub- 

 stantially holds good for the outflow of fibres throughout consider- 

 able regions of the cord, but that it is not always applicable to 

 great lengths of the cord, for the brachial plexus may be consti- 

 tuted in a region which is near the head end in comparison with 

 the place of origin in other individuals, while in the same individual 

 the sciatic plexus may be constituted in a region which is for it 

 comparatively far back. No exception to the principle was found 

 in the sense that a given efferent fibre which in one individual is 

 anterior to some other particular fibre is ever in any individual of 

 the same species posterior to it. Sherrington, C. S., Proc, Boy. 

 Soc, LI. 1892, p. 76. This principle of Herringham's is analogous 

 to that which in the much simpler case of Variation in vertebrae 

 was pointed out on p. 107. It was stated that in such Homceotic 

 variation no gaps are left. If a vertebra assumes a cervical cha- 

 racter, it is the 1st dorsal, and so on. 



*09, The following noteworthy case is described by Herringham in 

 an infant. It should be borne in mind that to a normal brachial 

 plexus the I Vth nerve gives a small communication, the Vth, Vlth, 

 Vllth, VIII th and IXth give large cords, while the Xth (or Hnd 

 dorsal) gives a minute fibre only. In this abnormal specimen, on 

 the left side the part from the Xth was as large as that from the 

 IXth, and this was as large as the Vlllth, whereas the natural 

 proportion of VIHth to IXth is about 2 to 1. The musculo-cuta- 

 neous received from the Vllth, instead of from the Vth and Vlth 

 only as more commonly found ; the median received no Vlth ( v. 

 supra); the teres major was supplied by the Vllth alone, instead 

 of by the Vlth; the circumflex received from the Vllth, instead 

 of Vth and Vlth alone as seen in' 43 cases without any other ex- 

 ception; the musculo-spiral was formed by the Vllth, VIHth and 

 IXth, instead of by the Vlth, Vllth and VIHth (and sometimes 

 even Vth) ; the deep branch in the hand received from both VIHth 



