All around the oral opening  eleven muscles are laid out: one initially, of annular form, the labial or orbicular one of the lips, which governs its occlusion then a series of ten others which from the various areas of the face, come to fit on its circumference like so many convergent rays. They are, from top to bottom: the common elevator of the wing of the nose and the upper lip; the very elevator of the upper lip; the canine one; the minor zygomatic muscle; the big zygomatic; the buccinator; the risorius; the triangular one of the lips; the square of the chin; the muscle of the bunch of the chin.