118. The lower extremity of the os femoris, being thicker than the
rest of the bone, and protected from the action of external bodies
by a thinner covering of soft parts, is yet better secured from
fractures than the other parts, for the following reasons: 1st, because
counter-strokes, so frequently the cause of fractures of the body
and neck of the bone, can affect this part but rarely: 2dly, because
the os femoris, being more moveable at a distance from the centre of
its motions, yields more easily to whatever strokes and impressions
it there receives: 3dly, because motion, when distributed through a
greater bulk of matter, has less power to destroy its continuity.
§ XVIII.