Course and distribution of the lingual nerve in the ventral tongue region: Anatomical considerations for frenectomy

The aim of this study was to elucidate the sublingual and intralingual courses of the lingual nerve (LN) in the ventral tongue region, providing a clinical guide for safe surgical procedures such as frenectomy. We evaluated 16 specimens (32 sides) by gross observation after detailed dissections, and a further 6 specimens were examined after Sihler staining. All specimens were harvested from embalmed Korean cadavers. We classified the innervation patterns of the LN into 5 types and confirmed the distribution of the LN in the tip of the tongue. The classification of the LN was made with reference to a line formed by the interlacing of the styloglossus and genioglossus muscles. Based on the course of LN and the presence of a tiny twig (twigs directly innervating the ventral mucosa of the tongue, TM) directly innervating the sublingual mucosa, the course of the LN was classified as being straight, curved, or vertical and with or without the TM. Straight, curved, and vertical courses without the TM were seen in 9.4%, 46.9%, and 18.8% of the cases, respectively. Straight and curved courses with the TM were observed in 6.3% and 18.8% of the cases, respectively. Sihler staining revealed that the tongue tip is innervated by the LN. These findings indicate that surgical manipulations at the ventral tongue region might damage the LN and result in numbness of the tongue tip, and provide a useful anatomic reference for various surgical procedures involving the ventral tongue region.