Symphysis menti

The external surface of the mandible is marked in the median line by a faint ridge, indicating the symphysis menti or line of junction of the two pieces of which the bone is composed at an early period of life.

This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of which is depressed in the center but raised on either side to form the mental tubercle.

It serves as the origin for the Geniohyoid and the Genioglossus.