On the Movement of Animals, Part One

whence it is gathered that the fibers of the muscles and the flesh are the same.

It should be noted, however, that muscular fibers differ from the fibers of tendons and membranes; insofar as the former are spongy and are always moistened by blood, by nervous juice, and by lymphatic fluid, differently than the latter; they also differ in structure and in a very different way of operating and in energy, as we shall explain in its proper place.

PROPOS. III.

In the last place, the different species of muscles must be recounted, and which parts act, and how, and through what directions; and first I note that two species of muscles are given: some are composed of bundles of fleshy threads, which constitute a rectangular prism, as $a$ in the first figure of the first plate, and these can be called straight prismatic.

Others constitute an oblique-angled prism, as $b$ in the second figure, and these can be called rhomboidal.

Others have decussated fibers composed of two rhomboidal ones, as $c$ in the third figure, and can be called decussated.

Others consist of two rhomboidal bundles not decussated, as $d$ in the fourth figure, and are called penniform.

Others consist of fibers scattered orbicularly, and are called radiate.

Others are round, similar to rings, and are called circular sphincters.