Located in the face, the orbicularis oris muscle controls movements of the mouth and lips. Specifically, it encircles the mouth, originating in the maxilla (upper jaw and palate) and mandible (lower jaw) bones. The muscle inserts directly into the lips.
In common language, the orbicularis oris is often referred to as 'the kissing muscle.' It allows for facial expression, and more specifically, it is responsible for puckering the lips. While this action is a requirement for kissing, the puckering action is used in a number of other ways. For example, the lips must contract into a pucker to forcefully exhale, which is necessary for playing certain music instruments such as trumpets and other horns. The orbicularis oris muscle is also responsible for closing the mouth.
In the past, the muscle was thought to be a sphincter, which is a ring-like muscle used to open or close an area of the body. Recently, it has been found to not exactly meet that definition, even though it does perform sphincter-like opening and closing actions.
The muscle is supplied by the seventh cranial nerve, as well as the buccal branch of the facial nerve.