Symphysis menti

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Symphysis menti
Symphysis menti (Gray190 edit)).png
Anterior view of mandible, showing symphysis menti (red broken line)
Medial surface of the left half of the mandible, dis-articulated from the right side at the symphysis menti.
Latin symphysis mandibulae
Gray's p.172
TA A02.1.15.004
FMA 75779
Anatomical terms of bone

In human anatomy, the external surface of the mandible is marked in the median line by a faint ridge, indicating the symphysis menti, mandibular symphysis, or line of junction of the two pieces of which the bone is composed at an early period of life. It is not a true symphysis as there is no cartilage betweent the two sides of the mandible.

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 muscles.

Other animals[edit]

Humpback skeleton showing the flexible "slingshot" symphysis present in baleen whales

When filter feeding, the baleen whales, of the suborder Mysticeti, can dynamically expand their oral cavity in order to accommodate enormous volumes of sea water. This is made possible thanks to its mandibular skull joints, especially the elastic mandibular symphysis which permits both dentaries to be rotated independently in two planes. This flexible jaw, which made the titanic body sizes of baleen whales possible, is not present in early whales and most likely evolved within Mysticeti.[1]

See also[edit]





  • Fitzgerald, Erich M. G. (2012). "Archaeocete-like jaws in a baleen whale". Biol. Lett. 8 (1): 94–96. doi:10.1098/rsbl.2011.0690. 

This article incorporates text from a public domain edition of Gray's Anatomy.