EXAMINATION OF SOME SPINAL NERVES 105 
great as may be the overlap of the fields of nerve-roots tliree segments distant one from another. 
If fig. 7, p. 98, be compared as in fig. 13 with fig. 11, p. 103, it will be seen that in the palm 
the region of triple overlap marked in the latter is greater than the medio-ulnar overlap in the 
former ; and similarly in the fingers, if we set aside the communication between ulnar and 
median in the forearm, whicii is of only exceptional occurrence in Man. It is also notable 
that the region of triple overlap, which is the central region of double overlap, strikes a line on 
Fig. 15 
I 2 
OverLip of the skin-fields of median and ulnar nerve-trunks (i) compared with overlap of the 
skin-fields of the Vllth cervical and Ist thoracic segmental nerves (2). 
the palm which leads to and includes the medius digit, whereas the peripheral nerve-trunk overlap 
strikes a line leading to and taking in part of a different digit, namely, the annulus. This, again, 
points to there being no real correspondence between the two systems of overlap. 
The answer arrived at to the question set is, therefore, that where examined an overlap of 
the skin-fields of adjacent peripheral nerve-trunks has been found, but that it is very small as 
compared with the overlapping of the skin-fields of adjacent nerve-roots, and bears no significant 
topographical relation to the overlapping of the root-fields. On the other hand, I have shown 
o 
