Branching Patterns of Mental Nerve in Newborns

In classical textbooks of Anatomy, the mental nerve is considered to be the terminal or main branch of the inferior alveolar nerve, especially trifurcate with no designated names as soon as it emerges from the mental foramen. The textbooks define the innervation area of the mental nerve regionally without naming its terminal branches. Nomina Anatomica designates 3 terminal branches of mental nerve as "labial, gingival, and mental branch" but offers no description about their distribution on the mandible. In the present study, bilateral dissections were performed on the lower lip specimens of 20 newborns for 40 mental nerves to determine the branching types of mental nerve. Although anatomy textbooks indicate that mental nerve divides into 3 branches, the authors noted that mental nerve branched into 1, 2, or 3 branches at or right after its exit from the mental foramen. Branching patterns were typed in 13 different subclasses under 3 main groups (Form I-II-III). Moreover, the branching patterns that could not be included in one of these 3 main groups were defined as "Complex Form." The most common type of branching that the authors observed was Form II, which had 2 terminal branches with an incidence of 41.9% (16 specimens). The next frequently encountered type was Form III, having 3 terminal branches, and it was detected in 32.0% of patients (12 specimens). The least common form was Form I, which had 1 terminal branch with a frequency of 15.8% (6 specimens). The unclassified group, Complex Form, was found 10.5% (4 specimens).