Orbicularis oris muscle

The orbicularis oris muscle is a muscle that surrounds the mouth and serves to close the mouth and pucker the lips. It is often considered a sphincter, but it is not as it is more complex and contains fibers derived from several nearby muscles.

Origin
The orbicularis oris originates at the center of the anterior surface of the maxilla above the lips and the mandible below them, and at the modiolus of the mouth.

Insertion
The orbicularis oris inserts at the mucous membrane at the edge of the lips.

Innervation
The orbicularis oris is innervated by the buccal branch of the facial nerve (CN VII).