Page:Popular Science Monthly Volume 36.djvu/701

Rh When we make any very violent bodily effort, as to put on a tight boot, or to open a tightly closed door, besides contracting the muscles of the arm, we stiffen the neck, clinch the teeth, and press the lips close upon one another. It is very evident that these muscles do not in any way contribute to the attainment of the end proposed; but at the moment when the man is calling upon all his strength and energy to overcome a difficulty by means of a bodily effort, the intensity of his will is manifested not only in the muscles that serve to produce the desired effect, but also in all the muscular apparatus of the body. Every muscle contracts; and, of course, the contraction of the weaker muscles is neutralized by that of the smaller ones. These simultaneous movements, without intention or object, appear more evidently in the facial muscles, and notably in the vigorous muscles of mastication. In all violent or difficult movements we are accustomed, by the contraction of the muscles, to press the lower jaw against the upper, as if we were tearing or breaking some hard object.

The fact that we have noticed in connection with the bitter trait that the movement of the lower jaw is accompanied with a similar movement of the mouth—is likewise observed in the pinched trait. As in the former case we remove, as far as possible, not only the upper maxillary from the lower maxillary, but also the upper lip from the lower; so, in the latter, we press the lower maxillary against the upper, and the lower lip against the upper. In consequence of the contraction of the orbicular labial muscle and of the incisor muscles, the lips are closely shut and their red edges are turned within; but at the same time the lower lip is energetically pressed against the upper, by the action of the two levators of the chin. These muscles start from the upper edge of the lower jaw, near the median incisives, directing their fibers downward and outward, and lose themselves in the skin of the chin. They lift the middle of the lower half of the orbicular labial muscle, and press the skin of the chin closely against the bone. In consequence of this movement, the middle of the lower lip seems to be raised, and simultaneously two wrinkles or indentations appear, which, beginning at the middle of the lower lip,