558 THE DISTRIBUTION AND USE OF TENDINOUS STRUCTURE. 
humerus and extensor pedis pulls down the bone, or causes the 
humerus to be flexed upon the radius whenever the knee is bent ; 
and I have not been able to flex the metacarpal bone while another 
person held the humerus stationary. And by this arrangement, 
though the distance from the head of the radius to the foot is 
increased, yet, if the space be measured over the anterior of the 
muscles, there it will be found, in consequence of the compulsatory 
yielding of the humerus, to be the same during every position of 
the limb. The provisions made below the knee render traction 
on the contractile fibre impossible if the fetlock is flexed when the 
leg is extended — a circumstance of not unfrequent occurrence when 
a horse stumbles — all force being then resisted by the tendons 
and their accessory ligaments alone. 
Nature has, however, provided similar means to protect the 
delicate serous membranes associated with tendon from being in- 
jured by the spasmodic energy of the muscles. The different uses 
of the bands found united to the tendons of the horse’s leg are 
easily ascertained by the direction of the fibres, which, as in arti- 
cular ligament, always run in the line of that force they are de- 
signed to restrain. From the posterior of the radius there will be 
found to arise tendinous cords, which are inserted into the flexor 
tendons. These, perfectly distinct from the bands to which I have 
before alluded, are obviously intended to limit and restrain the 
action of the muscles. Also, from the inner side of the head of 
the cannon bone a broad band takes its origin, which, passing ob- 
liquely upwards to the front of the knee, blends with the tendon of 
the extensor pedis, this likewise restraining or regulating the energy 
of the muscle. 
Thus, gentlemen, I have endeavoured to point out to you struc- 
tures which have, so far as I know, been hitherto unobserved, and 
I hope I have not over-rated their importance. If I have done so, 
your experience will speedily correct my error; but, unfortunately, 
our anatomy needs practical application no less than assiduous in- 
vestigation, for the field is as yet but rudely explored. I wished 
to prove that in the living body each structure has its use, and 
that the functions of white fibrous tissue and muscular fibre, though 
the two may be associated, yet in their offices remain distinct. 
Thus, while fibrous tissue is formed to resist and to sustain as a 
passive agent, muscular fibre, being active, is protected from all 
excitement, that it may obey the dictates of the will. 
I may not conclude this Essay without making the most ample 
and grateful acknowledgment of the assistance I have received, 
while prosecuting my inquiries, from Messrs. Jeykell, Crowly, 
Jones, Crabbe, and especially from Mr. Varnell, to whose skill in 
dissection I am indebted for many of the facts which have enabled 
me to illustrate my opinions. 
