Most expressions are intensified when the mouth is opened—the mouth is usually opened to add something to a response. The smile, when vocalization is added, becomes the laugh; the frightened mouth opens to emit a scream; the sad mouth utters a cry. Even the relaxed open mouth, depending on the look of the eye and brow, may suggest the face of astonishment or passion. A stroll through the department of primitive art in a large museum reveals that much of the work is in agreement with this principle—in masks, sculptures, and carvings from around the world, few mouths are closed. These are faces full of energy and often strong emotion.
The levator labii superioris (the sneering muscle), the zygomatic major (the smiling muscle), and the ris-orius/platysma (the lip stretcher), are the key muscles in the creation of open-mouthed expressions. The depressor labii inferioris, which pulls the lower lip downward, also plays a minor role.
Opportunities for inadvertently replacing one expression with another in the open mouth are numerous, as with the closed mouth. An attractive open mouth can grade into a sneering mouth with very little difficulty; a slight extra bend in the corner can turn a laugh into a scream.
The point of reference for our description of the open mouth is the way it looks when it is merely open, with none of the surrounding muscles at work. We'll thus have a basis for comparison with open mouths that are not relaxed.
The lips part slightly when we breathe. When people are engaged in physical activity, their lips part more often as their breathing rate rises. The average person, walking, opens the mouth fairly often: the average jogger keeps the mouth open. The association of slightly parted lips with sexual activity (which can increase breathing rates quite a lot) is one that has been exploited by advertisers for years.
The dropping of the lower jaw pulls the lips apart. As the lower jaw drops, space appears between the teeth. The corner where the two lips meet is pulled downward slightly and inward. To reach this new joining point, the upper and lower lip alter in shape.
The upper lip, pressed against the fixed upper jaw, changes less than the lower. The moving lower lip has to stretch and bend more to reach the mouth corner. The lip, composed of two sections, tends to bend in the center and curve gently upward toward the two corners, making a V-shape. It also appears thicker: the lifting of the upper lip expose its wide upper surface. The upper lip bends where its three sections meet; the outer wings seem to hinge off the center, making a square-arch shape. The more the mouth opens, the more sharply the wings swing down.
The net result is an oval-shaped opening, with just the tips of the teeth showing. This contrasts sharply with the way the mouth is shaped in laughing, crying, or angry shouting, when the inner margin is much more squared-off and angular, and whole rows of teeth, either upper or lower, are exposed. Large areas of teeth showing always indicate an expression in progress.
The dropping of the jaw also affects the shape of the whole lower half of the face. It gets longer, of course, and the outline has a stretched and often hollowed-out look to it, as the skin spans between its points of support on the cheekbone and the chin. The chin has not only moved downward, but backward as well—this is clear from a side view. From in front, the face appears narrower.
Was this article helpful?
Realize Your Dream of Becoming a Professional Pencil Drawing Artist. Learn The Art of Pencil Drawing From The Experts. A Complete Guide On The Qualities of A Pencil Drawing Artist.