Canine tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, fangs, or (in the case of those of the upper jaw) eye teeth, are relatively long, pointed teeth. However, they can appear more flattened, causing them to resemble incisors and leading them to be called incisiform. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the maxillary bone.

The four canines in humans are the two maxillary canines and the two mandibular canines.

Canine tooth
Azawakh K9
This dog's longer pointed cuspids or "fangs" show why they are particularly associated with canines.
Details
Identifiers
Latindentes canini
MeSHD003481
TAA05.1.03.005
FMA55636
Anatomical terminology

Details

There are four canine teeth: two in the upper (maxillary) and two in the lower (mandibular) arch. A canine is placed laterally to each lateral incisor. They are larger and stronger than the incisors, and their roots sink deeply into the bones, and cause well-marked prominences upon the surface.

The crown is large and conical, very convex on its labial surface, a little hollowed and uneven on its lingual surface, and tapering to a blunted point or cusp, which projects beyond the level of the other teeth. The root is single, but longer and thicker than that of the incisors, conical in form, compressed laterally, and marked by a slight groove on each side. The lingual surface also presents two depressions on either side of the surface separated by a ridge in between; these depressions are known as mesial and distal lingual fossae.

In humans, the upper canine teeth (popularly called eye teeth, from their position under the eyes[1]) are larger and longer than the lower, and usually present a distinct basal ridge. Eruption typically occurs between the ages of eleven and twelve years. Occasionally they are congenitally missing.[2]

From a facial aspect, maxillary canines are approximately one millimetre narrower than the central incisor. Their mesial aspects resemble the adjacent lateral incisors, while their distal aspects anticipate the first premolars. They are slightly darker and more yellow in color than the other anterior teeth. From a lingual aspect, they have well developed mesial and distal marginal ridges and a well-developed cingulum. A prominent lingual ridge divides the lingual aspect in half and creates the mesial and distal lingual fossae between the lingual ridge and the marginal ridges. From a proximal aspect, they resemble the incisors, but are more robust, especially in the cingulum region. Incisally, they are visibly asymmetrical, as the mesial incisal edge is slightly shorter than the distal incisal edge, which places the cusp slightly mesial to the long axis of the tooth. They are also thicker labiolingually than mesiodistally. Because of the disproportionate incisal edges, the contacts are also asymmetrical. Mesially, the contact sits at the junction of the incisal and middle third of the crown, while distally, the contact as more cervical, in the middle of the middle third of the crown.

The lower canine teeth are placed nearer the middle line than the upper, so that their summits correspond to the intervals between the upper canines and the lateral incisors. Eruption typically occurs between the ages of nine and ten years of age.

From a facial aspect, the mandibular canine is notably narrower mesiodistally than the maxillary one, even though the root may be just as long (and at times bifurcated). A distinctive feature is the nearly straight outline this tooth has compared to the maxillary canine which is slightly more bowed. As in the maxillary canine, the mesial incisal edge (or cusp ridge) is shorter than the distal side, however, the cusp is displaced slightly lingual relative to the cusp of the maxillary canine. Lingually, the surface of the tooth is much more smooth compared to the very pronounced surface of the maxillary canine, and the cingulum is noted as less developed.

Sexual dimorphism

With many species, the canine teeth in the upper or lower jaw, or in both, are much larger in the males than in the females, or are absent in females, except sometimes a hidden rudiment. Certain antelopes, the musk-deer, camel, horse, boar, various apes, seals, and the walrus, offer instances.[3]

In non-mammals

In non-mammals, teeth similar to canines may be termed "caniniform" ("canine-shaped") teeth.

Additional images

3D Medical Animation Still Showing Types of Teeth

Medical animation showing Canine teeth and their arrangement in the mouth of an adult human being.

Illu mouth

Mouth (oral cavity)

Gray157

Left maxilla. Outer surface.

Gray187

Base of skull. Inferior surface.

Gray1001

Unerupted permanent teeth underlie the deciduous teeth.

See also

References

This article incorporates text in the public domain from page 1116 of the 20th edition of Gray's Anatomy (1918)

  1. ^ "eye-tooth". Oxford English Dictionary Online. Oxford University Press. 1989.
  2. ^ Borzabadi-Farahani, A. (2015). "Bilateral agenesis of maxillary permanent canines: Review of the literature". J Orthod Sci. 4 (1): 26–9. doi:10.4103/2278-0203.149614. PMC 4314837. PMID 25657989.
  3. ^ The Descent of Man. Charles Darwin. s:Descent of Man/Chapter XVII

External links

Boreogomphodon

Boreogomphodon is an extinct genus of traversodontid cynodonts from the Late Triassic of the eastern United States. Fossils have been found from the Turkey Branch Formation in Virginia.

Canine fossa

In the musculoskeletal anatomy of the human head and neck, lateral to the incisive fossa is a depression called the canine fossa. It is larger and deeper than the comparable incisive fossa, and is separated from it by a vertical ridge, the canine eminence, corresponding to the socket of the canine tooth; the canine fossa gives origin to the levator anguli oris.

Canine space

The canine space (also termed the infra-orbital space), is a fascial space of the head and neck (sometimes also termed fascial spaces or tissue spaces). It is a thin potential space on the face, and is paired on either side. It is located between the levator anguli oris muscle inferiorly and the levator labii superioris muscle superiorly. The term is derived from the fact that the space is in the region of the canine fossa, and that infections originating from the maxillary canine tooth may spread to involve the space. Infra-orbital is derived from infra- meaning below and orbit which refers to the eye socket.

Chororapithecus

Chororapithecus is an extinct hominine genus that lived during the Miocene and is represented by one species, Chororapithecus abyssinicus. It is believed to be the earliest known species of the tribe Gorillini. It was originally interpreted as living about 10 to 10.5 million years ago, and its existence was thought to indicate that the last common ancestor between the human/chimpanzee lineage and gorillas may have lived greater than 10 to 11 million years ago, which is at least 2 million years earlier than the previously thought date of divergence of about 8 million years ago. However, a subsequent study by Katoh et al. (2016) dated its fossils to ~8 million years ago.The only evidence found of this extinct ape is currently nine fossilized teeth of at least three individuals, recovered from the Chorora Formation which runs along the southern Afar Depression of Ethiopia (the same place where the remains of Lucy were discovered in 1974). Analysis of eight molars (two of them fragmented) and a canine tooth show that their structure is partly similar to modern gorillas.The researchers compared the make-up of the teeth to those of other current and fossil apes, and concluded that the new ape fossils were possibly those of a species of gorilla which ate mostly high-fiber plants, and that the fossil species is likely a 'direct ancestor' of the gorillas currently living in Africa. Alternatively, the idea that the finds are the remains of early hominins has not been ruled out entirely.

Chuka man-eating tiger

The Chuka man-eating tiger was a male Bengal tiger responsible for the death of three boys from Thak village in the Ladhya Valley in 1937. It was shot by Jim Corbett in April 1937 who noted that the animal had a broken canine tooth and several gunshot wounds in various parts of his body.

Dinocynodon

Dinocynodon is an extinct genus of titanosuchian therapsids.

The oval outline of the cross section of the canine tooth can hardly be a sufficient character to justify a new generic name. It can only be identified as a titanosuchian.

Dog-tooth

A dog-tooth or "dogtooth pattern", in architecture, is an ornament found in the moldings of medieval work of the commencement of the 12th century, which is thought to have been introduced by the Crusaders from the East. The earliest example is found in the hall at Rabbath Ammon in Moab (c. 614) built by the Sassanians, where it decorates the arch molding of the blind arcades and the string courses. The pattern consists of 4 flower petals forming a square or diamond shape with central elements. The petals have the form of the pointed conical canine tooth, eye tooth or cuspid.

In the apse of the church at Murano, near Venice, it is similarly employed. In the 12th and 13th centuries it was further elaborated with carving, losing therefore its primitive form, but constituting a most beautiful decorative feature. In Elgin Cathedral the dogtooth ornament in the archivolt becomes a four-lobed leaf, and in Stone church, Kent, a much more enriched type of flower. The term has been supposed to originate in a resemblance to the dog tooth violet, but the original idea of a projecting tooth is a sufficient explanation."Dogtooth" is also a woven fabric pattern which resembles a canine tooth.

Ganlea

Ganlea is a fossil primate from central Myanmar, formerly known as Burma. Its age is about 38 million years, living during the late Eocene epoch. Ganlea belongs to the group of anthropoids (i. e. humans, apes and monkeys), and is in the family Amphipithecidae. It is older than any other known anthropoid from Africa, and is the second oldest known from Asia. Its remains consist of teeth and jawbones belonging to 10 to 15 individuals found near the city of Bagan in the central part of the country.The teeth of Ganlea have many diagnostic features that help to show its relations with other anthropoids. It is thought to be closely related to the genera Myanmarpithecus, Pondaungia and Siamopithecus, both found from the same area as Ganlea. In all of these genera, the canine tooth is enlarged and compressed anteroposteriorly, making it quite wide. A great deal of tooth wear has been observed in Ganlea, which has been viewed as an adaptation for consuming nuts and seeds, similar to the modern Saki monkey. The large size of the canine tooth in Ganlea gives it the specific name "megacanina".

Phylogenetic analyses conducted upon the description of Ganlea suggest that the amphipithecids are closely related to New World monkeys (Platyrrhini) and the extinct propliopithecids. This places it firmly within Haplorrhini. Darwinius, a primate recently described and quickly claimed a transitional fossil of great importance to human ancestry, is a member of the Adapiformes, which has recently been viewed as a transitional group between Strepsirrhini and Haplorrhini. This means that Ganlea is more closely related to modern monkeys and apes than Darwinius is.

Because of its age, Ganlea has been called a missing link that places the origin of all anthropoids (including humans) in Asia rather than Africa as was previously thought. However, doubts have been raised towards the claim that it is the ancestor of all other anthropoids. Other extinct primates such as Eosimias seem to be more basal members than Ganlea. Because Ganlea is a true anthropoid, it has been seen as more likely to be a direct ancestor of monkeys and apes (and thus humans) than Darwinius would. However, the phylogenetic analysis that was conducted on it suggests that it is too derived to have been an ancestral anthropoid, and its close relation with New World monkeys seems to imply that it was not a human ancestor, as apes are believed to have evolved from Old World monkeys.

Kiwuri (Abaroa)

Kiwuri (Aymara kiwucode: aym promoted to code: ay canine tooth or tusk, -ri a suffix, also spelled Quiburi) is a mountain in the Andes of Bolivia which reaches a height of approximately 4,540 m (14,900 ft). It is located in the Oruro Department, Eduardo Abaroa Province, Challapata Municipality. The Waylla Q'awa which originates northeast of the mountain flows along its northern slope.

Kiwuri (Potosí)

Kiwuri (Aymara kiwucode: aym promoted to code: ay canine tooth or tusk, -ri a suffix, also spelled Quibure) is a 4,284-metre-high (14,055 ft) mountain in the Bolivian Andes. It is located in the Potosí Department, Antonio Quijarro Province, Porco Municipality, northwest of the village of Qullpa (Kollpa). The Ch'unchull Mayu originates near the mountain. It flows along its western slope.

Kiwuri (Totora)

Kiwuri (Aymara kiwucode: aym promoted to code: ay canine tooth or tusk, -ri a suffix, also spelled Kiburi, Quiburi) is a 4,302-metre-high (14,114 ft) mountain in the Andes of Bolivia. It is located in the Oruro Department, San Pedro de Totora Province.

Panthera shawi

Panthera shawi is an extinct prehistoric cat, of which a single canine tooth was excavated in Sterkfontein cave in South Africa by Robert Broom in the 1940s. Broom described it in 1948 using the scientific name Felis shawi.

It is thought to be the oldest known Panthera species.

Phaq'u Kiwuta

Phaq'u Kiwuta (Aymara phaq'u, paqu, p'aqu light brown, reddish, blond, dark chestnut, kiwu canine tooth or tusk, -ta a suffix, other spellings Pacokeuta, Paco Keuta, Pakokiuta, Pakokiwuta) is a mountain in the Andes, about 5,589 m (18,337 ft) high. It is located in the Cordillera Real of Bolivia in the La Paz Department, Los Andes Province, Batallas Municipality, Kirani Canton. It is situated south-west of the mountain Wila Lluxi, south-east of Warawarani and north of a lake named Quta Thiya in some maps. Other prominent mountains nearby are Jisk'a Pata and Janq'u Uyu in the north, and Wila Lluxita and Mullu Apachita in the north-east, all of them higher than 5,000 m.

Sexual dimorphism in non-human primates

Sexual dimorphism describes the morphological, physiological, and behavioral differences between males and females of the same species. Most primates are sexually dimorphic for different biological characteristics, such as body size, canine tooth size, craniofacial structure, skeletal dimensions, pelage color and markings, and vocalization. However, such sex differences are primarily limited to the anthropoid primates; most of the strepsirrhine primates (lemurs and lorises) and tarsiers are monomorphic.

Sneer

A sneer is a facial expression of scorn or disgust characterized by a slight raising of one corner of the upper lip, known also as curling the lip or turning up the nose. In The Expression of Emotions in Man and Animals, Charles Darwin defined a "sneer" as "the upper lip being retracted in such a manner that the canine tooth on one side of the face alone is shown" Darwin related the sneer to the snarl observed in non-human animals, particularly carnivores, observing that:

The uncovering of the canine tooth is the result of a double movement. The angle or corner of the mouth is drawn a little backwards, and at the same time a muscle which runs parallel to and near the nose draws up the outer part of the upper lip, and exposes the canine on this side of the face. The contraction of this muscle makes a distinct furrow on the cheek, and produces strong wrinkles under the eye, especially at its inner corner. The action is the same as that of a snarling dog; and a dog when pretending to fight often draws up the lip on one side alone, namely that facing his antagonist.It is suggested that the sneer is a universal expression of contempt and that Darwin was the first to observe this.

Cats may be observed to sneer, though this is probably related to the Flehmen response.

Tuqma

Tuqma (Quechua for canine tooth, also spelled Tujma) is a mountain in the Bolivian Andes which reaches a height of approximately 2,800 m (9,200 ft). It is located in the Cochabamba Department, Mizque Province, Mizque Municipality, near the border to the Carrasco Province, Pocona Municipality. Tuqma lies south of Misk'i. The Wanaku Mayu ("guanaco river") flows along its northern slope.

Tuqma Urqu

Tuqma (Quechua tuqma canine tooth, urqu mountain, "canine tooth mountain", also spelled Tucma Orkho) is a 2,822-metre-high (9,259 ft) mountain in the Bolivian Andes. It is located in the Cochabamba Department, Mizque Province, Mizque Municipality. The Tuqma River or Tuqma Mayu (Quechua) which originates northwest of the mountain, south of a peak named Tuqma flows along its western slope.

Nomenclature
Teeth
Maxillary teeth
Mandibular teeth
Parts

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