Beyond the Mandibular Canal: A Narrative Review of Inferior Alveolar Nerve Variations and Their Clinical Significance.

The inferior alveolar nerve (IAN) is commonly presented as a relatively constant branch of the mandibular nerve that gives rise to the mylohyoid nerve (MHN), enters the mandibular foramen, follows a single mandibular canal, and terminates as mental and incisive branches. However, direct human anatomical evidence shows substantially greater complexity. This critical narrative review synthesizes cadaveric, microdissection, histological, imaging, and osteological evidence on proximal IAN roots, relationships with the maxillary artery, communications with neighboring mandibular nerve branches, MHN-derived accessory pathways, intramandibular fascicular organization, and neural structures associated with accessory canals or foramina. PubMed/MEDLINE was searched through August 20, 2026, with focused supplementary searches, Google Scholar citation searching, and reference-list screening; direct human neural evidence was prioritized over osseous inference. Histological studies show that a grossly single IAN can contain separately organized neural components, whereas proximal dissections demonstrate double roots, artery-through-nerve configurations, recurrent branches, and communications with the lingual and auriculotemporal nerves. The MHN may extend beyond its conventional motor territory, communicate with the lingual nerve, and use accessory mandibular pathways. Conversely, an accessory foramen or canal does not by itself establish the presence of an accessory IAN branch because some channels are predominantly vascular. The evidence is therefore best interpreted as a branching neuro-osseous continuum rather than a canal-only model. Clinically, these variants may help explain selected patterns of incomplete anesthesia or unexpected sensory and surgical anatomy, but bony imaging alone should not be used to infer causation.