Lõpp

Läpp, in anatomical terms, refers to the two fleshy folds that surround the opening of the mouth. The two lips—the upper lip (labium superioris oris) and the lower lip (labium inferioris oris)—form the boundary between the external skin and the internal oral mucosa.

Anatomy and structure: The external surface of the lips is skin, typically thin and with sparse hair, containing sebaceous glands and sweat glands. The central area, the vermilion border, has a thinner epidermis and a highly pigmented, keratinized appearance. The lips house the orbicularis oris muscle, a circular muscle important for movements of the mouth, speech, and sealing the oral opening. The submucosa connects the lips to the oral cavity and contains minor salivary glands and connective tissue. The inner surface is lined by mucosa continuous with the oral cavity.

Blood supply and innervation: The lips are supplied by the facial artery through the superior and inferior labial arteries. Sensory innervation comes from the trigeminal nerve: the upper lip mainly via the superior labial nerve (a branch of the infraorbital nerve, V2) and the lower lip via the inferior labial nerve (a branch of the mental nerve, V3).

Function: The lips assist in speech and articulation, eating and swallowing, and in expressing emotion. They help seal the mouth, protect the oral entrance, and contribute to tasting and manipulating food.

Clinical notes: Common conditions include cheilitis (lip inflammation), angular cheilitis at the corners of the mouth, and herpes labialis (cold sores). Lip cancer, particularly on the lower lip, is associated with sun exposure. Treatments range from moisturizers and protective balms to antivirals and surgical interventions for more significant lesions.