§ I.
1. The fore-arm, composed of two bones, neither of them very strong,
and covered below by a small quantity of soft parts, is exposed
still more than the humerus, to the action of external bodies, and
is articulated at the upper end in such a manner, as not to yield,
like it, in every direction to the impulses which it receives. From
these considerations, it is one of those parts where fractures most
frequently occur, and, in a comparative view of affections of this kind
in the Hotel-Dieu, it has oftentimes held the first place.
2. It would be useless to mention here the disposition of the bones
which compose the fore-arm, their irregularly prismatical form, their
thickness unequally distributed, their direction obviously different,
and their motions differently combined. It is sufficient to observe,
that, for the perfection of one part of these motions, a space, wide in
the middle, and narrow at the ends, must separate the two bones, that,
without this space the radius, impeded in its movements on the cubitus,
would compress the muscles, restrain their action, and would be
unable to perform the motions of pronation and supination; whence the
fore-arm, being confined, as it were, to mere flexion and extension,
would not, in its uses, correspond to our wants.
These things being premised, we will observe, that fractures of the
fore-arm may have their seat, 1st, in both bones at the same time;
2dly, they may occupy but one of them: hence three kinds of fractures
more or less different in their phenomena, their consequences, and
their treatment.