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THOMPSON YATES LABORATORIES REPORT 
Motor Cells exhibiting in the self-same Segment marked Inequality of Accessibility to local reflex 
bressor Impulses^ innervate antergetic Muscles. 
Of the functional groups of motor neurons in the cord, some, in view of the actions of the 
muscles they innervate, may be termed synergetic w^ith some, antergetic to this or that other. 
Those of the flexors of knee may thus be said to act in synergy w^ith those of the flexors of the 
hip, but in antergy to those of extensors of knee ; also in a certain measure to those of extensors 
of hip. These last are in synergy w^ith the extensors of the knee, but in antergy to flexors of hip ; 
also in certain measure to those of knee. The groups of motor neurons which in one and the same 
spinal segment exhibit marked inequality of local reflex excitability innervate antergetic muscles. So much 
is this the case that in reflex movements of local spinal origin, it is the rule for only one set of an 
antagonistic couple of muscles to be thrown into contraction, and especially for only one group of 
antagonistic groups to be contracting at the same time. I have already alluded to this, and pointed 
it out in a previous paper,* but will add here further illustrations. 
Flexion of ankle by dorsal flexors, the post-tibial and crural muscles remaining absolutely without 
contraction, in response to excitation of internal plantar nerve (or external plantar, or cutaneous of 
musculo-cutaneous generally). 
Contraction of those parts of quadriceps extensor (rectus internus and fascialis) which flex the hip, 
while the part that extends the knee remains absolutely without contraction, in response to excitation 
of long saphenous nerve. Contraction of flexors of elbow, the tricepsf remaining quite flaccid. 
Contraction of the triceps of the arm, while biceps and brachialis remain absolutely without 
contraction, in response to excitation of the afferent root of the Vlllth cervical nerve. 
Contraction of the extensors of the wrist, the flexors remaining absolutely without contraction, in 
response to touching the fore-pad of the Cat. 
Contraction of the flexors of the elbow, the extensors remaining absolutely without contraction, in 
response to thermal stimulation of the palm (Cat). 
Contraction of the adductors (pector. maj. and latiss. dorsi) at shoulder, the abductors remaining 
quite slack (deltoid). 
In dealing with rules of irradiation in spinal reflexes, I have mentioned reasons for believing 
the groups of motor neurons innervating small pieces of musculature, acting synergetically upon 
the self-same joint, to be commonly treated by the spinal action as entities, *nd employed as units 
in these spinal reflexes. From that and the foregoing it follows that in adjoining spinal segments 
the groups of motor nerve-cells contemporaneously selected for excitation by spinal reflex action 
are synergetic, not antergetic. This is, of course, the reverse of what, since WinslowJ and 
DucHENNE,§ has been common belief concerning the co-ordination of ' willed ' movements of Man, 
but it agrees with the co-ordination which I have proved to take place in the Frog.|| I have 
shown that in the limb, while for muscles antergetic at the distal joints the groups of motor 
neurons largely overlap each other in segmental position, the groups of muscles antergetic at the 
proximal joints of the limb do not so largely segmentally overlap. Hence the reflex spinal 
discrimination between motor neuron-groups for the antagonistic musculature of the proximal 
limb-joints involves a field wider than merely three adjoining segments. 
* ' Journ. of Physiol.,' vol. 13, p. 621. § 'Physiologic cles Mouvements.' 
f Except for a part which retracts the arm without extending the elbow. Paris, 1867. 
\ ' An Anatomical Exposition of the Structure of the Human Body.' 4to. || 'Journ. of Physiol.,' vol. 13, 1892. 
London, 1749. 
