mental spine

n.
  1. A slight projection located in the middle line of the rear surface of the body of the lower jawbone that gives attachment below to the geniohyoid muscle and above to the genioglossus muscle.genial tubercle
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.