57 Mental Nerve Block
The mental nerve is a branch of the inferior alveolar nerve from the third division of the trigeminal nerve. The inferior alveolar nerve enters the mandibular foramen to travel within the mandibular canal and form the mental nerve. At its exit from the mental foramen, the mental nerve is divided into several branches.1 The mental nerve emerges from the mental foramen to supply the chin, lower lip, and teeth. The mental nerve can provide innervation to the lower incisors.2
The mental foramen lies about halfway between the upper and lower borders of the mandible, although the position of the foramen relative to the mandible varies with age.3,4 Elderly patients who are edentulous have decay of the alveolar ridge. This brings the mental foramen closer to the upper border of the mandible. A severely resorbed alveolar ridge can make identification of the mental foramen difficult.
Suggested Technique
The mental foramen typically has posterior or right-angled inclination.5 When the nerve emerges at right angles, it is funnel shaped. The longest diameter of the mental foramen is about 3 mm.6 The presence of multiple mental foramina is rare, being observed in about 2% of cases.3–57
