It may take more muscles to frown than to smile, but smiling is more work. When we smile, the zygomatic major attempts to slide the entire orbicularis oris (the muscle that includes and circles the lips) back toward the ear, underneath the cheeks. Where cheeks and orbicularis oris meet, a deep crease, the signature wrinkle of the smile, develops.
When we smile, the lips are stretched against the teeth, whose shape shows through. This shape is similar to the block form (right)—flattened in the front and turned sharply to the side. Just as a rubber band stretched against that form loses any kinks or sags it may have had, the lips become more uniform in the smile. Compare the LBL in a relaxed face to the smile: the kinks are stretched out.
A. Cheeks widest just above level of base of nose.
B. Skin tightly stretched between cheek and chin. Line is concave; almost no concave lines appear in relaxed face.
C. Lips are pulled upward toward nose.
D. Chin appears longer and broader. Smile stretches skin over chin, smoothing it. Lower lip has lifted toward nose, exposing more chin.
E. Attachment of muscle.
F. Cheek piled highest off face here.
G. Dimples are located on side of face; usually, dimples are deeper on one side than the other.
H. LBL almost completely unkinked; compare with LBL of relaxed mouth.
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