50 
CONTRACTILITY OF TENDONS. 
spection of the special directions imparted to the parts shows 
that these much oftener relate to the isolated action of this 
or that tendon, than to the collective action of the muscles 
that move the joint. This retraction, as in the case of that 
of muscles, is but the pathological expression of a physio- 
logical property possessed by the tendons. 
3. Physiological facts. — The tendon of the patella is separ- 
able into two distinct portions, just as if they were separate 
tendons, which may be termed infra- patellar and supra- 
patellar tendons. It happens not unfrequently, as a conse- 
quence of disease, that the patella becomes anchylosed, or 
fixed to the femur, isolating from the muscular extremity of 
the tendon, the contraction proper to the latter. On observ- 
ing -what takes place in such persons, during efforts to raise 
the limb, we find that, at the same time, the extensor muscles 
of the thigh contract, the infra-patellar tendon — i. e. f the 
portion situated between the immoveable patella and the tibia 
— participates in this contraction, becoming sensibly hardened 
and shortened, both to the touch and sight. "We may, indeed, 
observe upon ourselves the contractions of this infra-patellar 
tendon during certain attitudes. If, while in the sitting pos- 
ture, we place our fingers along its track, we find it become 
distended and hardened during every effort made to raise the 
leg, still keeping it at the same degree of flexion, the patella 
remaining immoveable and strongly applied against the femur. 
4. Nature of the contractility . — The contractility of tendons 
is not identical with that of muscles, for it cannot be induced 
by galvanism. There are, too, other contractile organs, not 
excitable by galvanism, such as the dartos . The muscles 
themselves present sometimes an exceptional state ; for, after 
saturnine paralysis, they continue to contract under the in- 
fluence of the will, but are completely insensible to the influ- 
ence of galvanism. By means of two experiments, M. 
Guerin endeavours to point out the limits of both muscular 
and tendinous contraction ; and he considers that the latter 
comes into operation when the weight of the body to be 
moved induces resistance. Hence he terms this tendinous 
contractility the contraction de resistance , indicating thus its 
true experimental character, and its difference from voluntary 
contraction. — Gazette Medicate , No. X, 1856. 
