A cusp is a pointed, projecting, or elevated feature. In

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

s, it is usually used to refer to raised points on the crowns of teeth. The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps.

In humans

A cusp is an occlusal or incisal eminence on a tooth. Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps. In certain populations the maxillary molars, especially first molars, will possess a fifth cusp situated on the mesiolingual cusp known as the Cusp of Carabelli. One other variation of the upper first premolar is the 'Uto-Aztecan' upper premolar. It is a bulge on the buccal cusp that is only found in Native American Indians, with highest frequencies of occurrence in Arizona. The name is not a dental term; it comes from a regional linguistic division of Native American Indian language groups.

Cusps on the molars of therian mammals

There are four main cusps found on the molars of the upper

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

theria Theria ( or ; ) is a scientific classification, subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the Placentalia, placental mammals) and the metatherians (including the marsupials) but excludes the egg-lay ...

n mammals.

Hypocone

The ''hypocone'' is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

for the overall grinding and tearing of foods using the occlusal (chewing side) of the tooth surface during occlusion or mastication (chewing). Its strength is due to the thickness of the enamel which differs among species of hominids. The hypocone appears to have evolved independently more than twenty times in different mammal groups during the Cenozoic period.

Metacone

The ''metacone'' is a

cusp A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth. Cusp or CUSP may also refer to: Mathematics * Cusp (singularity), a singular point of a curve * Cusp catastrophe, a branch of bifu ...

on the molars of the upper

in hominids. It is found at the buccal distal area of the tooth. The crests between the cusps are adaptations for slicing food during occlusion or mastication (chewing).

Paracone

The anterior of the three cusps of a primitive upper molar that in higher forms is the principal anterior and outside cusp.

Protocone

The ''protocone'' is founding the molars of the upper

in Placental and

Marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...

vertebrates.Gavin Prideaux, "Systematics and Evolution of the Sthenurine Kangaroos" (April 1, 2004). UC Publications in Geological Sciences. Paper vol_146. http://repositories.cdlib.org/ucpress/ucpgs/vol_146 p.16 It is found at the mesiolingual area of the tooth. The crests between the cusps are adaptations for slicing food during occlusion or mastication (chewing).

References

Bibliography

* Ash, Major M.; Nelson, Stanley. ''Wheeler'S Dental Anatomy, Physiology and Occlusion'', 8th edition. {{Authority control Parts of tooth