Notes
Muscles of the Cheeks and Mouth
Sections
Muscles of the Cheeks and Mouth
Muscles of facial expression that act on the cheeks and mouth. These muscles attach to bone, the skin of the nose and the lips, and into other muscles of the face.
These muscles are innervated by the facial nerve, CN VII.
Orbicularis oris
Zygomaticus major
Zygomaticus minor
Levator labii superioris
Buccinator
Risorius
Mentalis
Depressor labii inferioris
Orbicularis oris
Encircles the lips.
Orbicularis oris arises from the skin and other muscles around the mouth and inserts into the skin of the lips; it closes the lips (as in a pucker).
Zygomaticus major
Arises laterally from the zygomatic bone (aka the cheek bone) and inserts at the angle (the superior corner) of the mouth; zygomaticus major pulls the corner of the lips laterally and superiorly (as in a smile).
Zygomaticus minor
Arises from the anterior aspect of the zygomatic bone and inserts medial to zygomaticus major into the skin of the upper lip. Because of its more medial orientation, zygomaticus minor elevates the upper lip.
Levator labii superioris
Arises from the maxilla, inferior to the orbital margin, and inserts into the skin of the upper lip, medial to the zygomaticus muscles. Because levator labii superioris runs inferior and adjacent to the skin of the nose, it also flares the nostrils.
It is helpful to know that levator refers to "elevate"; "labii superioris" refers to the upper lips.
Buccinator
A thin, sheet-like muscle that arises laterally in the cheek from the maxilla and mandible and inserts into the lips; buccinator compresses the cheeks, which is important during chewing.
Risorius
Arises laterally from connective tissues covering the jaw and inserts at the angle of the mouth; risorius retracts the lips at the angle of the mouth.
Mentalis
Arises from the inferior edge of the body of the mandible and inserts into the skin of the chin and lower lip; mentalis protrudes the lower lip (think of an exaggerated pout).
Depressor labii inferioris
Arises from the anterolateral side of the mandibular body and extends medially to insert into the skin of the lower lip; depressor labii inferioris depresses the lower lip.