The external surfaces of the lips have three distinct regions: the skin, the vermilion, and the oral mucosa. The cosmetically important junction of the skin and the red portion of the lip is called the vermilion border. The orbicularis oris muscle surrounds the mouth. Its integrity is responsible for retaining the saliva inside the mouth, producing the bilabial sounds of speech, and providing important facial expressions. The infraorbital nerve supplies the upper lip and the mental nerve supplies the lower lip. Both are branches of the trigeminal nerve and can easily be blocked by regional anesthetic techniques. The lips are richly supplied by the labial arteries. Z
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