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Topic

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Mental nerve

The mental nerve is a key sensory branch of the inferior alveolar nerve, itself a division of the mandibular nerve (cranial nerve V3). It emerges from the mental foramen on the anterior aspect of the mandible and supplies sensation to the chin, lower lip, and adjacent gingiva. Understanding the anatomy, function, and imaging characteristics of the mental nerve is crucial for radiologists, dentists, and oral surgeons for both diagnostic and procedural planning.

Synonyms

  • Terminal branch of the inferior alveolar nerve

  • Mandibular sensory branch

  • Mental branch of CN V3

Function

  • Provides sensory innervation to the skin of the chin

  • Supplies the mucosa and skin of the lower lip

  • Innervates the labial gingiva of the mandibular anterior teeth and premolars

  • Transmits tactile, pain, and temperature sensations from its area of supply

MRI Appearance

  • T1-weighted images:

    • The mental nerve appears as a small, linear, low-to-intermediate signal structure within the fat of the mental canal, just anterior to the mental foramen. Surrounding fat offers high signal contrast.

  • T2-weighted images:

    • The nerve itself remains low to intermediate signal, while the adjacent fat appears hyperintense, making the nerve distinguishable as a hypointense structure within the canal.

  • STIR (Short Tau Inversion Recovery):

    • Suppresses fat signal, highlighting edema or nerve pathology. The normal mental nerve remains low signal, while pathological changes (e.g., inflammation or neuroma) may appear hyperintense.

CT Appearance

  • Conventional CT:

    • The mental nerve itself is not directly visualized but is inferred by its location within the mental canal. The bony mental foramen is well-demonstrated on axial and sagittal views.

MRI images

Mental nerve mri axial image