Relation of mental nerve with mandibular branch of the facial nerve

The aim of this study is to elucidate the detailed anatomical relation of mental nerve with marginal mandibular branch of the facial nerve. Twenty-three hemi-faces of adult Korean cadavers (11 Male and 7 female) were dissected. All locations of crossing (C) of marginal mandibular branch of the facial nerve and mental nerve were measured below the inferior verge of the lower vermillion (V): a vertical distance (V-Gn) between V and gnathion (Gn) and horizontal distance (V-OC) between V and oral commissure (OC). The mental foramen located at 19.8 +/- 4.4 mm below the inferior verge of the lower vermillion (V) and 34.3 +/- 5.2 mm laterally from the midline. In all specimens there were found interconnections between marginal mandibular branch of the facial nerve and mental nerve. The number of connecting site was 8.26 +/- 2.49. Microscopically, both of the nerve branches had a common epineurium, but the perineurium separated. V-Gn and the vertical distance between V and the connecting point (C) was in the ratio of approximately 2:1, and V-OC and the horizontal distance from V:C was an equal ratio. The proximity of the mental nerve and marginal mandibular branch of the facial nerve to each other draws an attention as operating the mental area.