ESSAY III. OF THE MUSCLES OF THE FACE IN MAN AND IN ANIMALS. In the limbs THE fleshy or muscular part of the animal frame is a peculiar fibrous substance; and of the various textures, it alone possesses power of contraction, and consequently of producing motion. and trunk the muscles are distinct and powerful, having their tendons attached to the bones, and performing the various voluntary movements. In the face they are more delicate; their action being merely to operate on the skin, the lips, and eyelids, they require less power; and that power is not always, as in the muscular exertions of the body and limbs, directly under the will, but often involuntary and inseparably united to the conditions or affections of the mind. It is this latter consideration which gives so much interest to this subject. By the form of the head we shall presently find that nature has been provident of an excellence in that organ on which the mind and superior intelligence of man depend, so in the muscles of the face there is a provision for a superiority of expression; and F thus the very spirit by which the body is animated, and the signs of the various affections of the mind, shine out in the countenance. This superiority of expression in the face some would have to be an accidental result; they say, that the muscles prepared for mastication and speaking give such a superiority of muscular apparatus to the human face, as to account for the superiority of expression. But I have put that question to rest, by observations and experiments upon the nerves*. That the muscles used in speaking are those of expression may be readily allowed; but there are also muscles of expression, which have nothing to do with the voice, and which are purely indicative by signs of the operations of the mind. Further, we shall find that the countenance of man is not merely pre-eminent by the possession of powers peculiar to him, but also by this, that he stands intermediate betwixt the two great classes of animals, possessing the muscular system of both combined. It is only necessary for the reader to understand that the muscles are formed of distinct packets of fibres or fasciculi, and that their extremities are called their origin and insertions: the fixed extremity, attached generally to some point of bone, is the origin; the extremity which moves is the insertion of the muscle. *Philos. Transactions. |