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Topic

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Lower lip

The lower lip is the anterior portion of the oral cavity that forms the inferior boundary of the mouth. It consists of skin, subcutaneous tissue, muscles (primarily the orbicularis oris), minor salivary glands, and mucosa. It plays a critical role in speech, mastication, facial expression, and sensation. Understanding its anatomy, function, and imaging characteristics is essential for radiologists, dentists, oral surgeons, and ENT specialists for both diagnostic and procedural planning.

Synonyms

  • Labium inferius oris

  • Inferior labial region

  • Mandibular lip

Function

  • Provides sensory innervation to the lower lip skin and mucosa via the mental nerve

  • Facilitates speech and articulation through controlled movement

  • Assists in mastication and oral seal

  • Contributes to facial expression

  • Transmits tactile, pain, and temperature sensations from the skin and mucosa

MRI Appearance

T1-weighted images:

  • The lower lip muscles appear intermediate signal intensity.

  • Subcutaneous fat appears hyperintense, providing contrast with surrounding muscle.

  • Mucosa is slightly hypointense, while skin is low signal.

  • Pathology, such as tumors or edema, may appear hypo- to hyperintense relative to muscle.

T2-weighted images:

  • Muscle remains intermediate signal, while fat is bright and mucosa may show slightly increased signal.

  • Edema, inflammation, or cystic lesions appear hyperintense, allowing clear identification of pathological changes.

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal to highlight pathology.

  • Normal muscle and mucos

MRI images

Lower lip mri image -img-00000-00000