59.2 STRING-HALT-ITS DOUBTFUL PATHOLOGY. 
Now, liavc we any evidence to bring forward in support of 
these views ? In the first place, has string-halt ever super¬ 
vened immediately upon fracture of some of the vertebra! ? 
We have already alluded to a case by Mr. Percival, and 
which, I think, is conclusive, both because he seems to have 
had no doubt of its being so, and also because it agrees with 
physiological reasoning. 
Ill the second place, we may refer again to the case men¬ 
tioned by Mr. Goodwin, which, although not so conclusive as 
the last named, is nevertheless not to be lost sight of. It 
requires no particular stretch of the imagination to suppose 
that, at the anchylosed part of the vertebrie, the holes of 
conjugation might become diminished in size, and their 
margins perhaps rendered uneven from spiculae of bone, and 
thus the nerves which passed through them become irritated. 
Or the string-halt might have been caused, as was sup¬ 
posed, by undue'' pressure of the spinal cord, in consequence 
of the abnormal narrow condition of the spinal canal. I 
could bring several similar cases forward in support of this 
idea. Then we have the evidence of the experimental phy¬ 
siologist, who shows that, by pinching the roots of the motor 
nerves within the spinal canal, previous to their joining 
their ganglia, the muscles they supplj’' with motor stimulus 
are thrown into convulsive spasms; or if the sentient nerves 
going to any particular muscle be pricked, reflex nervous 
power, with muscular contraction, is the result. Such being 
the effect of excited nervous action caused by irritation, we 
only require a persistent abnormal excitant to produce, when 
the limb is about to be moved, undue muscular contraction. 
. In the next place, to show the effects of irritating the 
sciatic nerve, let the following experiment be tried. Lay 
bare the first division, the anterior tibial, at that part where it 
crosses the peroneus muscle, about one inch and a half below 
the head of the fibula, and pinch it with a pair of forceps, 
and the muscles it supplies, namely, the pero*neus, the flexor, 
metatarsi, and the extensor pedis, will spasmodically contract, 
as in string-halt. But Avholly divide this nerve at the point 
alluded to, and in a few hours string-halt will have subsided 
altogether, these muscles being paralysed. I think this is 
fair evidence that to cause string-halt some of the fibres of 
the sciatic nerve must be suddenly irritated, and also that 
the muscles alluded to are those that are involved in pro¬ 
ducing this phenomenon. 
Filaments from this division of the sciatic nerve can be 
traced to the front of the hock—chieflv sentient, of course— 
and who, I would ask, that has seen a moderate share of 
