An opening on the lateral (side) part of the body of the mandible (lower jaw), inferior to (below) the second premolar teeth, through which the nerves to the chin and blood vessels pass: The mental foramen transmits the mental nerves and vessels to the skin of the face.

A mental foramen (natural opening, usually through the bone) functions as the passage of blood vessels and a nerve on the outside of the lower jaw on each side near the chin.