The general muscular system very evidently forms two great divisions,
differing essentially from each other, by the vital forces that animate
them, by their external forms, by their mode of organization, and
especially by the parts they perform, the one in animal life, and
the other in organic. We shall not then consider them together. Let
us begin by the examination of the muscles of animal life; these are
spread out in great number in the human body. No system as a whole, is
of more considerable size; no one occupies more space in the economy.
Besides the numerous regions that the muscles fill, they are generally
spread out under the skin, and partake, as it were, of the functions
of this organ, protect like it the subjacent parts, like it bear with
impunity the action of external bodies, and can even be divided in a
more or less considerable extent, without the general functions of
life suffering from it; which renders them very fit to defend the
deep-seated organs, whose lesion would be very injurious.