The red of the lips, the mucosa, the commissures and the labial sulcus are the major anatomical structures of the lips. The red of the lips contains, unlike the mucosa and the adjacent skin, neither perspiratory or sebaceous glands nor hair follicles, and appears reddishly due to the very thin epithelium. The labial commissures are located directly behind the labial angle / angulus oris and include a mucosal area which has a diameter of about 1.5 cm. The labial mucosa reaches from the red of the lips until 1 cm above the vestibular sulci.
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