The lips surround the mouth which is the entrance into the gastrointestinal system. The oral cavity provides the ability to eat, drink, and speak. Digestion begins in the mouth through mastication and the action of salivary enzymes. The musculature controlling the mouth is complex and interdigitating, making their repair and reconstruction challenging. The muscles which seal the oral cavity, elevate, or depress the lips are described. Motor innervation of these muscles is provided by branches of the facial nerve (CNVII). Sensory innervation is provided by branches of the trigeminal nerve and cervical nerves. The facial artery, a branch of the external carotid, supplies this region.
