Muscles of the Lips

Buccinator

Contraction can pull the mouth corner backward and toward the side and can force the lip and cheek against the teeth

Risorius

Contraction draws the corner of the mouth backward and toward the side

Levator anguli oris (or caninus)

Contraction draws the corner of the mouth upward and toward the side and may raise the lower lip against the upper lip

Levator labii superioris

Contraction elevates the upper lip

Zygomatic minor

Contraction elevates the upper lip and pulls the corner of the mouth upward

Levator labii superioris alaeque nasi

Contraction of the lip segment elevates the upper lip (recall that the nasal segment dilates the anterior naris)

Zygomatic major

Contraction pulls backward on the corner of the mouth and lifts it upward and toward the side

Mentalis

Contraction pulls chin tissue upward, forces lower part of lower lip against the alveolar process of the mandible, and curls the lower lip outward Called the "pouting muscle"

Incisivus labii inferioris

Contraction pulls downward and inward on the corner of the mouth

Depressor anguli oris (or triangularis)

Contraction pulls the corner of the mouth downward and draws the upper lip downward toward the lower lip

Incisivus labii superioris

Contraction pulls the corner of the mouth upward and toward the midline

Depressor labii inferioris

Contraction pulls the lower lip downward and toward the side and may also cause the lower lip to turn outward

Platysma

Originates from a sheet of connective tissue within the neck above the clavicle (and may extend from farther below) and inserts on the lower edge of the mandible

Orbicularis oris

The only muscle of the lips that contains intrinsic fibers Forms a ring of muscle within the upper and lower lips Contraction can move the lips toward each other and forward (to closure), move the corners of the mouth in several directions, and force the lips and/or corners of the mouth against the teeth