CHAPTER III.

PHYSIOLOGICAL ANATOMY.

THE MUSCLES.


[Illustration: Fig. 19.
Muscular fillers highly
magnified.]

The _Muscles_ are those organs of the body by which motion is produced,
and are commonly known as _flesh_. A muscle is composed of _fascieuli_,
or bundles of fibers, parallel to one another. They are soft, varying in
size, of a reddish color, and inclosed in a cellular, membranous sheath.
Each _fasciculus_ contains a number of small fibers, which, when
subjected to a microscopic examination, are found to consist of
_fibrillae_, or little fibers; each of these fibrillae in turn being
invested with a delicate sheath. The fibers terminate in a glistening,
white _tendon_, or hard cord, which is attached to the bone. So firmly
are they united, that the bone will break before the tendon can be
released. When the tendon is spread out, so as to resemble a membrane,
it is called _fascia_. Being of various extent and thickness, it is
distributed over the body, as a covering and protection for the more
delicate parts, and aids also in motion, by firmly uniting the muscular
fibers. The spaces between the muscles are frequently filled with fat,