IN THE HUMAN FRAME. 
65 
the tibia. It protects both the tendon and the.joint from 
any injury which either might suffer by the rubbing of one 
against the other, or by the pressure of unequal surfaces. 
It also gives to the tendons a very considerable mechan¬ 
ical advantage, by altering the line of their direction, and 
by advancing it farther out from the centre of motion; and 
this upon the principles of the resolution of force, upon 
which principles all machinery is founded. These are its 
uses. But what is most observable in it is, that it appears 
to be supplemental, as it were, to the frame; added, as it 
should almost seem, afterward; not quite necessary, but 
very convenient. It is separate from the other bones; that 
is, it is not connected with any other bones by the com¬ 
mon mode of union. It is soft, or hardly formed, in infan¬ 
cy; and produced by an ossification, of the inception or 
progress of which no account can be given from the struct¬ 
ure or exercise of the part. 
VI. The shoulder-blade is, in some material respects, a 
very singular bone: appearing to be made so expressly 
for its own purpose, and so independently of every other 
reason. [PI. X. fig. 4.] In such quadrupeds as have no 
collar-bones, which are by far the greater number, the 
shoulder-blade has no bony communication with the trunk, 
either by a joint, or process, or in any other way. It does 
not grow to, or out of, any other bone of the trunk. It 
'does not apply to any other bone of the trunk; (I know not 
whether this be true of any second bone in the body, ex¬ 
cept perhaps the os hyoi'des.) [PI. X. fig. 5.] In strict¬ 
ness, it forms no part of the skeleton. It is bedded in the 
flesh; attached only to the muscles. It is no other than a 
foundation bone for the arm, laid in separate, as it were, 
and distinct, from the general ossification. The lower 
limbs connect themselves at the hip with bones which form 
a part of the skeleton; but this connexion, in the upper 
limbs, being wanted, a basis, whereupon the arm might 
be articulated, was to be supplied by a detached ossifica¬ 
tion for the purpose. 
I. The above are a few examples of bones made re¬ 
markable by their configuration: but to almost all the 
bones belong joints; and in these, still more clearly than 
in the form or shape of the bones themselves, are seen 
both contrivance and contriving wisdom. Every joint is a 
curiosity, and is also strictly mechanical. There is the 
hinge-joint, and the mortice and tenon joint; each as 
manifestly such, and as accurately defined, as any which 
can be produced out of a cabinet-maker’s shop; and one 
