Anatomical terminology is a form of scientific terminology used by anatomists and health professionals such as doctors. Anatomical terminology uses many unique terms and prefixes deriving from Ancient Greek and Latin; these terms can be confusing to those unfamiliar with them, but can be more precise, reducing ambiguity and errors. Since these anatomical terms are not used in everyday conversation, their meanings are less to change, less to be misinterpreted. To illustrate how inexact day-to-day language can be: a scar "above the wrist" could be located on the forearm two or three inches away from the hand or at the base of the hand. By using precise anatomical terminology such ambiguity is eliminated. An international standard for anatomical terminology, Terminologia Anatomica has been created. Anatomical terminology has quite regular morphology, the same prefixes and suffixes are used to add meanings to different roots; the root of a term refers to an organ or tissue. For example, the Latin names of structures such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for "two-headed", brachii as in the brachial region of the arm.
The first word describes what is being spoken about, the second describes it, the third points to location. When describing the position of anatomical structures, structures may be described according to the anatomical landmark they are near; these landmarks may include structures, such as the umbilicus or sternum, or anatomical lines, such as the midclavicular line from the centre of the clavicle. The cephalon or cephalic region refers to the head; this area is further differentiated into the cranium, frons, auris, nasus and mentum. The neck area is called cervical region. Examples of structures named according to this include the frontalis muscle, submental lymph nodes, buccal membrane and orbicularis oculi muscle. Sometimes, unique terminology is used to reduce confusion in different parts of the body. For example, different terms are used when it comes to the skull in compliance with its embryonic origin and its tilted position compared to in other animals. Here, Rostral refers to proximity to the front of the nose, is used when describing the skull.
Different terminology is used in the arms, in part to reduce ambiguity as to what the "front", "back", "inner" and "outer" surfaces are. For this reason, the terms below are used: Radial referring to the radius bone, seen laterally in the standard anatomical position. Ulnar referring to the ulna bone, medially positioned when in the standard anatomical position. Other terms are used to describe the movement and actions of the hands and feet, other structures such as the eye. International morphological terminology is used by the colleges of medicine and dentistry and other areas of the health sciences, it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research and medical care. The international morphological terminology refers to morphological sciences as a biological sciences' branch. In this field, the form and structure are examined as well as the changes or developments in the organism, it is functional.
It covers the gross anatomy and the microscopic of living beings. It involves the anatomy of the adult, it includes comparative anatomy between different species. The vocabulary is extensive and complex, requires a systematic presentation. Within the international field, a group of experts reviews and discusses the morphological terms of the structures of the human body, forming today's Terminology Committee from the International Federation of Associations of Anatomists, it deals with the anatomical and embryologic terminology. In the Latin American field, there are meetings called Iberian Latin American Symposium Terminology, where a group of experts of the Pan American Association of Anatomy that speak Spanish and Portuguese and studies the international morphological terminology; the current international standard for human anatomical terminology is based on the Terminologia Anatomica. It was developed by the Federative Committee on Anatomical Terminology and the International Federation of Associations of Anatomists and was released in 1998.
It supersedes Nomina Anatomica. Terminologia Anatomica contains terminology for about 7500 human gross anatomical structures. For microanatomy, known as histology, a similar standard exists in Terminologia Histologica, for embryology, the study of development, a standard exists in Terminologia Embryologica; these standards specify accepted names that can be used to refer to histological and embryological structures in journal articles and other areas. As of September 2016, two sections of the Terminologia Anatomica, including central nervous system and peripheral nervous system, were merged to form the Terminologia Neuroanatomica; the Terminologia Anatomica has been perceived with a considerable criticism regarding its content including coverage and spelling mistakes and errors. Anatomical terminology is chosen to highlight the relative location of body structures. For instance, an anatomist might describe one band of tissue as "inferior to" another or a physician might describe a tumor as "superficial to" a deeper body structure.
Anatomical terms used to describe location
Anatomical terms of location
Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. All vertebrates have the same basic body plan – they are bilaterally symmetrical in early embryonic stages and bilaterally symmetrical in adulthood; that is, they have mirror-image left and right halves if divided down the middle. For these reasons, the basic directional terms can be considered to be those used in vertebrates. By extension, the same terms are used for many other organisms as well. While these terms are standardized within specific fields of biology, there are unavoidable, sometimes dramatic, differences between some disciplines. For example, differences in terminology remain a problem that, to some extent, still separates the terminology of human anatomy from that used in the study of various other zoological categories. Standardized anatomical and zoological terms of location have been developed based on Latin and Greek words, to enable all biological and medical scientists to delineate and communicate information about animal bodies and their component organs though the meaning of some of the terms is context-sensitive.
The vertebrates and Craniata share a substantial heritage and common structure, so many of the same terms are used for location. To avoid ambiguities this terminology is based on the anatomy of each animal in a standard way. For humans, one type of vertebrate, anatomical terms may differ from other forms of vertebrates. For one reason, this is because humans have a different neuraxis and, unlike animals that rest on four limbs, humans are considered when describing anatomy as being in the standard anatomical position, thus what is on "top" of a human is the head, whereas the "top" of a dog may be its back, the "top" of a flounder could refer to either its left or its right side. For invertebrates, standard application of locational terminology becomes difficult or debatable at best when the differences in morphology are so radical that common concepts are not homologous and do not refer to common concepts. For example, many species are not bilaterally symmetrical. In these species, terminology depends on their type of symmetry.
Because animals can change orientation with respect to their environment, because appendages like limbs and tentacles can change position with respect to the main body, positional descriptive terms need to refer to the animal as in its standard anatomical position. All descriptions are with respect to the organism in its standard anatomical position when the organism in question has appendages in another position; this helps avoid confusion in terminology. In humans, this refers to the body in a standing position with arms at the side and palms facing forward. While the universal vertebrate terminology used in veterinary medicine would work in human medicine, the human terms are thought to be too well established to be worth changing. Many anatomical terms can be combined, either to indicate a position in two axes or to indicate the direction of a movement relative to the body. For example, "anterolateral" indicates a position, both anterior and lateral to the body axis. In radiology, an X-ray image may be said to be "anteroposterior", indicating that the beam of X-rays pass from their source to patient's anterior body wall through the body to exit through posterior body wall.
There is no definite limit to the contexts in which terms may be modified to qualify each other in such combinations. The modifier term is truncated and an "o" or an "i" is added in prefixing it to the qualified term. For example, a view of an animal from an aspect at once dorsal and lateral might be called a "dorsolateral" view. Again, in describing the morphology of an organ or habitus of an animal such as many of the Platyhelminthes, one might speak of it as "dorsiventrally" flattened as opposed to bilaterally flattened animals such as ocean sunfish. Where desirable three or more terms may be agglutinated or concatenated, as in "anteriodorsolateral"; such terms sometimes used to be hyphenated. There is however little basis for any strict rule to interfere with choice of convenience in such usage. Three basic reference planes are used to describe location; the sagittal plane is a plane parallel to the sagittal suture. All other sagittal planes are parallel to it, it is known as a "longitudinal plane".
The plane is perpendicular to the ground. The median plane or midsagittal plane is in the midline of the body, divides the body into left and right portions; this passes through the head, spinal cord, and, in many animals, the tail. The term "median plane" can refer to the midsagittal plane of other structures, such as a digit; the frontal plane or coronal plane divides the body into ventral portions. For post-embryonic humans a coronal plane is vertical and a transverse plane is horizontal, but for embryos and quadrupeds a coronal plane is horizontal and a transverse plane is vertical. A longitudinal plane is any plane perpendicular to the transverse plane; the coronal plane and the sagittal plane are examples of longitudinal planes. A transverse plane known as a cross-section, divides the body into cranial and caudal portions. In human anatomy: A transverse plane is an X-Z plane, parallel to the ground, which s
The horse is one of two extant subspecies of Equus ferus. It is an odd-toed ungulate mammal belonging to the taxonomic family Equidae; the horse has evolved over the past 45 to 55 million years from a small multi-toed creature, into the large, single-toed animal of today. Humans began domesticating horses around 4000 BC, their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses; these feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered Przewalski's horse, a separate subspecies, the only remaining true wild horse. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, colors, breeds and behavior. Horses' anatomy enables them to make use of speed to escape predators and they have a well-developed sense of balance and a strong fight-or-flight response.
Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and lying down, with younger horses tending to sleep more than adults. Female horses, called mares, carry their young for 11 months, a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training in harness between the ages of two and four, they reach full adult development by age five, have an average lifespan of between 25 and 30 years. Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance. There are more than 300 breeds of horse in the world today, developed for many different uses. Horses and humans interact in a wide variety of sport competitions and non-competitive recreational pursuits, as well as in working activities such as police work, agriculture and therapy. Horses were used in warfare, from which a wide variety of riding and driving techniques developed, using many different styles of equipment and methods of control.
Many products are derived from horses, including meat, hide, hair and pharmaceuticals extracted from the urine of pregnant mares. Humans provide domesticated horses with food and shelter, as well as attention from specialists such as veterinarians and farriers. Specific terms and specialized language are used to describe equine anatomy, different life stages and breeds. Depending on breed and environment, the modern domestic horse has a life expectancy of 25 to 30 years. Uncommonly, a few animals live into their 40s and beyond; the oldest verifiable record was "Old Billy", a 19th-century horse that lived to the age of 62. In modern times, Sugar Puff, listed in Guinness World Records as the world's oldest living pony, died in 2007 at age 56. Regardless of a horse or pony's actual birth date, for most competition purposes a year is added to its age each January 1 of each year in the Northern Hemisphere and each August 1 in the Southern Hemisphere; the exception is in endurance riding, where the minimum age to compete is based on the animal's actual calendar age.
The following terminology is used to describe horses of various ages: Foal: A foal of either sex less than one year old. A nursing foal is sometimes called a suckling and a foal, weaned is called a weanling. Most domesticated foals are weaned at five to seven months of age, although foals can be weaned at four months with no adverse physical effects. Yearling: A horse of either sex, between one and two years old. Colt: A male horse under the age of four. A common terminology error is to call any young horse a "colt", when the term only refers to young male horses. Filly: A female horse under the age of four. Mare: A female horse four years old and older. Stallion: A non-castrated male horse four years old and older; the term "horse" is sometimes used colloquially to refer to a stallion. Gelding: A castrated male horse of any age. In horse racing, these definitions may differ: For example, in the British Isles, Thoroughbred horse racing defines colts and fillies as less than five years old. However, Australian Thoroughbred racing defines fillies as less than four years old.
The height of horses is measured at the highest point of the withers. This point is used because it is a stable point of the anatomy, unlike the head or neck, which move up and down in relation to the body of the horse. In English-speaking countries, the height of horses is stated in units of hands and inches: one hand is equal to 4 inches; the height is expressed as the number of full hands, followed by a point the number of additional inches, ending with the abbreviation "h" or "hh". Thus, a horse described; the size of horses varies by breed, but is influenced by nutrition. Light riding horses range in height from 14 to 16 hands and can weigh from 380 to 550 kilograms. Larger riding horses start at about 15.2 hands and are as tall as 17 hands, weighing from 500 to 600 kilograms. Heavy or draft horses are at least 16 hands (64 inches, 16
Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and self-sharpening edges to pass by each other in a shearing manner. The modification arose separately in several groups of carnivorous mammals. Different pairs of teeth were involved in the separate modifications. In modern Carnivora, the carnassials are the modified fourth upper premolar and the first lower molar; these teeth are referred to as sectorial teeth. Humans lack carnassial teeth. Carnassial teeth are modified molars which are adapted to allow for the shearing of flesh to permit the more efficient consumption of meat; these modifications are not limited to the members of the order Carnivora, but are seen in a number of different mammal groups. Not all carnivorous mammals, developed carnassial teeth. Mesonychids, for example, had no carnassial adaptations, as a result, the blunt, rounded cusps on its molars had a much more difficult time reducing meat. Neither members of Oxyclaenidae nor Arctocyonidae had carnassial teeth.
On the other hand, carnivorous marsupials have carnassial teeth. Both the living Tasmanian devil and the extinct Tasmanian wolf possessed modified molars to allow for shearing, although the Tasmanian wolf, the larger of the two, had adaptation more similar to the modern dog; the Pleistocene marsupial lion had massive carnassial molars. A recent study concludes. Moreover, these carnassial molars appear to have been used, unlike in any other known mammal, to inflict the killing blow to the prey by severing the spinal cord, crushing the windpipe or severing a major artery. Like these true marsupials, the related borhyaenids of South America had three carnassial teeth involving the first three upper molars and the second through fourth lower molars. In the borhyaenids the upper carnassials appear to have been rotated medially around the anteriorposterior axis of the tooth row in order to maintain tight occlusional contact between the upper and lower shearing teeth. Creodonts have two or three pairs of carnassial teeth, but only one pair performed the cutting function: either M1/m2 or M2/m3, depending on the family.
In Oxyaenidae, it is m2 that form the carnassials. Among the hyaenodontids it is M2 and m3. Unlike most modern carnivorans, in which the carnassials are the sole shearing teeth, in the creodonts other molars have a subordinate shearing function; the fact that the two lineages developed carnassials from different types of teeth has been used as evidence against the validity of Creodonta as a clade. Modern carnivorous bats lack true carnassial teeth, but the extinct Necromantis had convergent teeth, in particular M1 and M2, which bore expanded heels and broad stylar shelves; these were suited for crushing over an slicing action. Though not superficially similar, the triconodont teeth of some early mammals such as eutriconodonts are thought to have had a function similar to those of carnassials, sharing a similar shearing function. Eutriconodonts possess several speciations towards animalivory, the larger forms such as Repenomamus and Jugulator fed on vertebrate prey; the "tooth lips" of clevosaurid sphenodontians such as Clevosaurus are described as "carnassial-like".
In modern carnivorans the carnassial teeth pairs are found on either side of the jaw and are composed of the fourth upper pre-molar and the first lower molar. The location these carnassial pairs is determined by the masseter muscle. In this position, the carnassial teeth benefit from most of the force generated by this mastication muscle, allowing for efficient shearing and cutting of flesh and muscle; the scissor-like motion is created by the movement between the carnassial pair when the jaw occludes. The inside of the fourth upper pre-molar passes by the outer surface of the first lower molar, thus allowing the sharp cusps of the carnassial teeth to slice through meat; the length and size of the carnassial teeth vary between species, taking into account factors such as: the size of the carnivorous animal the extent to which the diet is carnivorous the size of the chunk of meat that can be swallowed. The fossil record indicates the presence of carnassial teeth 50 million years ago, implying that Carnivora family members descend from a common ancestor.
The shape and size of sectorial teeth of different carnivorous animals vary depending on diet, illustrated by the comparisons of bear carnassials with those of a leopard. Bears, being omnivores, have a flattened, more blunt carnassial pair than leopards; this reflects the bear's diet, as the flattened carnassials are useful both in slicing meat and grinding up vegetation, whereas the leopard's sharp carnassial pairs are more adapted for its hypercarnivorous diet. During the Late Pleistocene – early Holocene a now extinct hypercarnivorous wolf ecomorph existed, similar in size to a large extant gray wolf but with a shorter, broader palate and with large carnassial teeth relative to its overall skull size; this adaptation allowed the megafaunal wolf to scavenge on Pleistocene megafauna. Wear and cracking of the carnassial teeth in a wild carnivore may result in the death of the individual due to starvation. Carnassial teeth infections are common in domestic dogs, present as abscesses. Extraction of the tooth and antibiotics are necessary to ensure that no further complications occur
Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development and classification of teeth fall within its purview. Tooth formation begins before birth, the teeth's eventual morphology is dictated during this time. Dental anatomy is a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment. There are 20 primary teeth and 28 to 32 permanent teeth, the last four being third molars or "wisdom teeth", each of which may or may not grow in. Among primary teeth, 10 are found in the maxilla and the other 10 in the mandible. Among permanent teeth, 16 are found in the other 16 in the mandible. Most of the teeth have distinguishing features. Tooth development is the complex process by which teeth form from embryonic cells and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is the same as in humans. For human teeth to have a healthy oral environment, dentin and the periodontium must all develop during appropriate stages of fetal development.
Primary teeth start to form between the sixth and eighth weeks in utero, permanent teeth begin to form in the twentieth week in utero. If teeth do not start to develop at or near these times, they will not develop at all. A significant amount of research has focused on determining the processes that initiate tooth development, it is accepted that there is a factor within the tissues of the first branchial arch, necessary for the development of teeth. The tooth bud is an aggregation of cells that forms a tooth and is organized into three parts: the enamel organ, the dental papilla and the dental follicle; the enamel organ is composed of the outer enamel epithelium, inner enamel epithelium, stellate reticulum and stratum intermedium. These cells give rise to ameloblasts, which produce the reduced enamel epithelium; the growth of cervical loop cells into the deeper tissues forms Hertwig's Epithelial Root Sheath, which determines the root shape of the tooth. The dental papilla contains cells. Additionally, the junction between the dental papilla and inner enamel epithelium determines the crown shape of a tooth.
The dental follicle gives rise to three important entities: cementoblasts and fibroblasts. Cementoblasts form the cementum of a tooth. Osteoblasts give rise to the alveolar bone around the roots of teeth. Fibroblasts develop the periodontal ligaments which connect teeth to the alveolar bone through cementum. Tooth development is divided into the following stages: the bud stage, the cap, the bell, maturation; the staging of tooth development is an attempt to categorize changes that take place along a continuum. This determination is further complicated by the varying appearance of different histologic sections of the same developing tooth, which can appear to be different stages. Teeth are named by their sets and arch, class and side. Teeth can belong to one of two sets of teeth: permanent teeth. "deciduous" may be used in place of "primary", "adult" may be used for "permanent". "Succedaneous" refers to those teeth of the permanent dentition. Succedaneous would refer to these teeth as a group. Further, the name depends upon.
The term, "maxillary", is given to teeth in the upper jaw and "mandibular" to those in the lower jaw. There are four classes of teeth: incisors, canines and molars. Premolars are found only in permanent teeth. Within each class, teeth may be classified into different traits. Incisors are divided further into lateral incisors. Among premolars and molars, there are first and second premolars, first and third molars; the side of the mouth in which a tooth is found may be included in the name. For example, a specific name for a tooth may be "permanent maxillary left lateral incisor." There are several different dental notation systems for associating information to a specific tooth. The three most commons systems are the FDI World Dental Federation notation, Universal numbering system, Palmer notation method; the FDI system is used worldwide, the universal is used in the United States. Although the Palmer notation was superseded by the FDI World Dental Federation notation, it overwhelmingly continues to be the preferred method used by dental students and practitioners in the United Kingdom.
It was termed the "Zsigmondy system" after the Austrian dentist Adolf Zsigmondy who developed the idea in 1861, using a Zsigmondy cross to record quadrants of tooth positions. The Palmer notation consists of a symbol designating in which quadrant the tooth is found and a number indicating the position from the midline. Permanent teeth are numbered 1 to 8, primary teeth are indicated by a letter A to E; the universal numbering system uses a unique number for each tooth. The uppercase letters A through T are used for primary teeth and the numbers 1 - 32 are used for permanent teeth; the tooth designated "1" is the right maxillary third molar and the count continues along the upper teeth to the left side. T
The domestic dog is a member of the genus Canis, which forms part of the wolf-like canids, is the most abundant terrestrial carnivore. The dog and the extant gray wolf are sister taxa as modern wolves are not related to the wolves that were first domesticated, which implies that the direct ancestor of the dog is extinct; the dog was the first species to be domesticated and has been selectively bred over millennia for various behaviors, sensory capabilities, physical attributes. Their long association with humans has led dogs to be uniquely attuned to human behavior and they are able to thrive on a starch-rich diet that would be inadequate for other canid species. Dogs vary in shape and colors, they perform many roles for humans, such as hunting, pulling loads, assisting police and military, companionship and, more aiding disabled people and therapeutic roles. This influence on human society has given them the sobriquet of "man's best friend"; the term dog is applied both to the species as a whole, any adult male member of the same.
An adult female is a bitch. An adult male capable of reproduction is a stud. An adult female capable of reproduction is brood mother. Immature males or females are puppies. A group of pups from the same gestation period is called a litter; the father of a litter is a sire. It is possible for one litter to have multiple sires; the mother of a litter is a dam. A group of any three or more adults is a pack. In 1999, a study of mitochondrial DNA indicated that the domestic dog may have originated from multiple grey wolf populations, with the dingo and New Guinea singing dog "breeds" having developed at a time when human populations were more isolated from each other. In the third edition of Mammal Species of the World published in 2005, the mammalogist W. Christopher Wozencraft listed under the wolf Canis lupus its wild subspecies, proposed two additional subspecies: "familiaris Linneaus, 1758 " and "dingo Meyer, 1793 ". Wozencraft included hallstromi – the New Guinea singing dog – as a taxonomic synonym for the dingo.
Wozencraft referred to the mDNA study as one of the guides in forming his decision. The inclusion of familiaris and dingo under a "domestic dog" clade has been noted by other mammalogists; this classification by Wozencraft is debated among zoologists. The origin of the domestic dog includes the dog's evolutionary divergence from the wolf, its domestication, its development into dog types and dog breeds; the dog is a member of the genus Canis, which forms part of the wolf-like canids, was the first species and the only large carnivore to have been domesticated. The dog and the extant gray wolf are sister taxa, as modern wolves are not related to the population of wolves, first domesticated; the genetic divergence between dogs and wolves occurred between 40,000–20,000 years ago, just before or during the Last Glacial Maximum. This timespan represents the upper time-limit for the commencement of domestication because it is the time of divergence and not the time of domestication, which occurred later.
The domestication of animals commenced over 15,000 years ago, beginning with the grey wolf by nomadic hunter-gatherers. The archaeological record and genetic analysis show the remains of the Bonn–Oberkassel dog buried beside humans 14,200 years ago to be the first undisputed dog, with disputed remains occurring 36,000 years ago, it was not until 11,000 years ago that people living in the Near East entered into relationships with wild populations of aurochs, boar and goats. Where the domestication of the dog took place remains debated, with the most plausible proposals spanning Western Europe, Central Asia and East Asia; this has been made more complicated by the recent proposal that an initial wolf population split into East and West Eurasian groups. These two groups, before going extinct, were domesticated independently into two distinct dog populations between 14,000 and 6,400 years ago; the Western Eurasian dog population was and replaced by East Asian dogs introduced by humans at least 6,400 years ago.
This proposal is debated. Domestic dogs have been selectively bred for millennia for various behaviors, sensory capabilities, physical attributes. Modern dog breeds show more variation in size and behavior than any other domestic animal. Dogs are predators and scavengers, like many other predatory mammals, the dog has powerful muscles, fused wrist bones, a cardiovascular system that supports both sprinting and endurance, teeth for catching and tearing. Dogs are variable in height and weight; the smallest known adult dog was a Yorkshire Terrier, that stood only 6.3 cm at the shoulder, 9.5 cm in length along the head-and-body, weighed only 113 grams. The largest known dog was an English Mastiff which weighed 155.6 kg and was 250 cm from the snout to the tail. The tallest dog is a Great Dane; the dog's senses include vision, sense of smell, sense of taste and sensitivity to the earth's magnetic field. Another study suggested; the coats of domestic dogs are of two varieties: "double" being common with dogs originating from colder climates, made up of a coarse guard hair and a soft down hair, or "single", with the topcoat only.
Breeds may have stripe, or "star" of white fur on their chest or underside. Regarding coat appearance or h
Maxillary first premolar
The maxillary first premolar is one of two teeth located in the upper jaw, laterally from both the maxillary canines of the mouth but mesial from both maxillary second premolars. The function of this premolar is similar to that of canines in regard to tearing being the principal action during mastication known as chewing. There are two cusps on maxillary first premolars, the buccal cusp is sharp enough to resemble the prehensile teeth found in carnivorous animals. There are no deciduous maxillary premolars. Around 10-11 years of age, the primary molars are shed and the permanent premolars erupt in their place, it takes about 3 years for the adult premolar and its root to calcify. In the universal system of notation, the permanent maxillary premolars are designated by a number; the right permanent maxillary first premolar is known as "5", the left one is known as "12". In the Palmer notation, a number is used in conjunction with a symbol designating in which quadrant the tooth is found. For this tooth, the left and right first premolars would have the same number, "4", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└".
The international notation has a different numbering system than the previous two, the right permanent maxillary first premolar is known as "14", the left one is known as "24". Ash, Major M. and Stanley J. Nelson, 2003. Wheeler’s Dental Anatomy and Occlusion. 8th edition