Topics

Topic

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Inferior alveolar nerve

The inferior alveolar nerve is a critical branch of the mandibular nerve (CN V3), itself a division of the trigeminal nerve. It supplies sensation to the lower teeth, lower lip, and chin. This nerve is of paramount importance in dental procedures and maxillofacial imaging, and its anatomical course is closely related to the mandibular canal, making its identification vital on radiological studies such as MRI and CT.

Synonyms

  • Inferior dental nerve

  • Mandibular dental nerve

  • IAN

Function

  • Provides sensory innervation to all mandibular teeth

  • Supplies sensation to the buccal gingiva (premolars, incisors, canine region)

  • Innervates the lower lip and chin via its terminal branch, the mental nerve

  • Motor innervation (via mylohyoid branch) to mylohyoid muscle and anterior belly of digastric

MRI Appearance

  • T1-weighted (T1):

    • Appears as a small, hypointense (low signal) tubular structure within the mandibular canal

    • Surrounded by slightly hyperintense marrow fat

  • T2-weighted (T2):

    • Typically low to intermediate signal

    • May show slightly higher signal than on T1, but remains hypointense relative to surrounding marrow

  • STIR (Short Tau Inversion Recovery):

    • Suppresses fat signal, highlighting nerve as a low-signal structure.

    • Useful for detecting nerve edema or pathology, which may appear as increased signal within or around the nerve

CT Appearance

  • Visualized indirectly as a linear, low-density (hypodense) structure within the radiolucent mandibular canal

  • The canal appears as a well-defined bony channel running from the mandibular foramen to the mental foramen

  • High-resolution CT or cone beam CT (CBCT) best demonstrates the canal and allows assessment of proximity to dental roots or lesions

MRI images

Inferior Alveolar Nerve mri axial image