The mandibular symphysis 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. The two mental tubercles along with the medial mental protuberance are collectively called the mental trigone.

This article incorporates text in the public domain from page 172 of the 20th edition of Gray's Anatomy (1918)