Injuries of nerves and their consequences - Reflex Sympathetic ...

ANATOMY OF NERVES. 23
the leg having been dragged off, while the tissue of the
thigh, save for the nerve rupture, remained intact. Actual
experiment on the dead body showed, according to Tillaux,
a like tendency on the part of the greater nerves to
tear apart at some point usually near or at a joint. Thus
the sciatic gives way where it runs under the pyramidal
muscle, at the line of the sciatic notch, and the median
and ulnar part at the bend of the elbow, when traction
has been made on a lower portion of their trunks. These
facts may, in rare instances, be of value to the surgeon,
and might possibly determine, in certain cases of torn
limbs, the point for amputation.
The toughness and elasticity of nerves are also shown
in some cases of disease and injury. Romberg and the
author just quoted remark upon the extent to which they
will stretch without breaking. Thus the median or ulnar
will gain 15 to 20 centimetres in length before parting.
I have also noticed many times, as other observers must
have done, the same physical quality in nerves; but it has
seemed to me far more important to know how far this
extension may go without loss of physiological properties
in the portion stretched. We have all had occasion to
watch the slow lengthening of nerves pushed aside by
morbid growths, but in these cases it is
probable that a
constant process of repair in the interstices of the nerve
accompanies the extension and limits the mischief. A
healthy nerve will bear an amount of pressure and handling,
which both in surgical and physiological operations
has occasioned me much surprise. Several years ago I
endeavored to estimate the limits of this capacity to endure
extension by a series of experiments on the sciatic
nerve of the rabbit.
I give a single experiment to illustrate these remarks.
The sciatic nerve of a rabbit was separated from the point
of exit down to the knee ;
it was then cut across at the