The platysma is a thin, broad sheet of muscle in the neck and lower face region. It extends from the collarbone and shoulder blade up to the corner of the mouth and lower lip. The platysma muscle is responsible for pulling the corners of the mouth downward and helping to tense the skin of the neck. The muscle also helps to lower the jaw and pull the lower lip downward. The platysma muscle is innervated by the cervical branch of the facial nerve (cranial nerve VII) and works in conjunction with other facial and neck muscles to produce a range of facial expressions and neck movements. Dysfunction or weakness of the platysma muscle can lead to difficulties with speech, eating, and facial expressions, such as frowning or puckering the lips, and can contribute to sagging or wrinkling of the skin in the neck region.