Muscles of Facial Expression
Nasalis:
- Originates on the maxilla and inserts on the nasal cartilage at the midline; it flares the nostrils.
Corrugator supercilii muscles:
- Originates on the frontal bone (specifically, from the medial supraorbital margin) and insert on the medial half of the eyebrows and laterally on the supraorbital margin on the frontal bone; they depress the eyebrows (and pull them medially).
Orbicularis oculi:
- Originates on the medial margin of the orbit (specifically, from the maxillary, frontal, and lacrimal bones), and inserts into the rim and skin of the orbit and eyelids; it moves the eyelids and surrounding skin to squint and close the eyes.
Frontalis:
- Originates on the frontal bone and skin of the eyebrows, and inserts into the galea aponeurotica (aka, the epicranial aponeurosis); it elevates the eyebrows, which wrinkles the forehead horizontally.
Orbicularis oris:
- Originates on the skin and other muscles around the mouth and inserts into the skin of the lips; it closes the lips.
Zygomaticus major:
- Originates on the lateral side of the zygomatic bone and inserts into the angle of the mouth; it draws the corner (aka, angle) of the lips laterally and superiorly.
Zygomaticus minor:
- Originates on the anterior aspect of the zygomatic bone and inserts into the skin of the upper lip, which it elevates.
Levator labii superioris:
- Originates on the maxilla (specifically, from the infraorbital margin), and inserts into the skin of the upper lip, which it elevates; it also dilates (flares) the nostrils.
Buccinator:
- Originates on the surfaces of the maxilla and mandible, and inserts into the lips; it compresses the cheeks.
Risorius:
- Originates on connective tissues on the lateral sides of the face and the skin of the cheeks and inserts into the angle of the mouth; it retracts the lips at the angle of the mouth.
Mentalis:
- Originates on the body of the mandible and inserts into the skin of the chin and lower lip, which it elevates and protrudes.
Depressor labii inferioris:
- Originates on the mandible (specifically, from the anterolateral body) and inserts into the skin of the lower lip, which it depresses.
Additional Information:
- Muscles around the mouth and cheeks blend into one another
- Cranial nerve VII innervates them.
- Cranial nerve VII (the facial nerve) innervates the muscles of the scalp, eyes, and nose.
- Bell's palsy occurs when CN VII is damaged; Belly's palsy results in asymmetrical paralysis of the muscles of facial expression.