The mandibular incisive foramen.

An anatomical variant in the region of the mental foramen is discussed. In these cases the inferior alveolar nerve divides into its two terminal branches only after it has exited through the mental foramen. The incisive nerve thus commences outside the mandible, and has a short extra-osseous course before it enters the mandible through a separate foramen on the same horizontal plane. For the distance between these two foramina there is no nerve supply within the mandible. The groove between the two foramina may be the remnants of the mandibular canal. The foramen through which the nerve enters the bone is a separate anatomical entity from the mental foramen and should be recognised as such. It is proposed that this foramen be named the mandibular incisive foramen.