ii8 THOMPSON YATES LABORATORIES REPORT 
spinal segments, and lies mainly in two segments, the 8th and 9th. As result of this arrangement, 
antagonistic muscles are represented in one and the same root, most so when they lie at the distal 
end of the limb, less when they lie at the proximal end of the limb. Similarly, to the skin 
covering the hip a longer series of spinal roots contributes sensory fibres than contribute to the 
skin covering the knee, and still more so than contribute to the skin covering ankle and digits. 
In the upper limb, to the skin covering shoulder seven spinal ganglia contribute, to that 
covering elbow, six, to that covering wrist, four, to that covering fingers (excluding thumb), 
three. Here, again, as a glance at the adjoining tabular statement shows, the long supply 
at shoulder is rendered still longer if we include the sensory ganglia supplying its musculature^ 
for then the gap in the middle of its skin series is filled up, and we get sensory nerve- fibres 
for muscles and skin of shoulder-joint supplied by as many as ten spinal ganglia, from 
the Ilird cervical to the IVth thoracic, inclusive. But if the muscular alferent nerve- 
fibres for the fingers are included, together with the digital cutaneous, the digital series is 
only increased from three segments up to four segments. Both distributions indicate the same 
general rule. The segmental representation in the motor spinal roots and in the spinal ganglia of 
the opposite movements and of the opposite surfaces of limb-joints, is an overlapping one, and the 
overlap is greater for the distal joints of the limb than for the proximal. I look upon this 
arrangement as merely the physiological side of a morphological disposition, which latter has 
considerable ontogenetic significance. 
Observations on the movements of the limb obtained in the Monkey by excitation of the 
separate individual cervico-brachial motor roots have been made first by Ferrier and Yeo,* later 
by FoRGUE and LANNEGRACE,t and by myself.J For the purpose of the present investigation I 
have extended my own experiments to the upper cervical roots which the above-named workers 
did not include in their investigations. My results are given in the subjoined table : — - 
1st Cervical Root. — No movement of limb proper. Lateral adduction-flexion of the neck toward 
the side stimulated without rotation of the head. 
Unci Cervical Root. — No movement or the limb proper. Lateral adduction-flexion of the neck 
toward the side stimulated, with some retraction. Little or no rotation of the head, 
but the chin may be turned slightly toward opposite axilla. 
Illrcl Cervical Root. — No movement of the limb proper. Lateral adduction-flexion of the neck 
toward the side stimulated, with marked retraction and a little turning of the neck, so 
that chin is thrust upward toward opposite side. 
IP'th Cervical Root. — Elevation of shoulder dragging it headward and toward the spinal column. 
Slight lateral adduction-flexion toward side stimulated, with marked retraction. 
When the shoulder is fixed the slight turning of the head toward the opposite side 
previously obtainable becomes more pronounced. 
* 'Proc. Roy. Soc.,' 1881. f ' Compt. Rendus,' 1884. 
I 'Proceedings Physiol. Soc.,' Febr., 1892. 'Jouin. of Physiol.,' xiii, 1892. 
