CHAPTER III.
PHYSIOLOGICAL ANATOMY.
THE MUSCLES.
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 fibrillæ, or little fibers; each of these fibrillæ 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, which gives roundness and beauty to the limbs. The muscles are of various forms; some are longitudinal, each extremity terminating in a tendon, which gives them a fusiform or spindle-shaped appearance; others are either fan-shaped, flat, or cylindrical.
