Teleology

From Wikipedia, the free encyclopedia

Plato and Aristotle, depicted here in The School of Athens, both developed philosophical arguments addressing the universe's apparent order (logos)

 

Teleology or finality is a reason or explanation for something in function of its end, purpose, or goal. It is derived from two Greek words: telos (end, goal, purpose) and logos (reason, explanation). A urpose that is imposed by a human use, such as that of a fork, is called extrinsic. Natural teleology, common in classical philosophy but controversial today, contends that natural entities also have intrinsic purposes, irrespective of human use or opinion. For instance, Aristotle claimed that an acorn's intrinsic telos is to become a fully grown oak tree.

Though ancient atomists rejected the notion of natural teleology, teleological accounts of non-personal or non-human nature were explored and often endorsed in ancient and medieval philosophies, but fell into disfavor during the modern era (1600–1900). In the late 18th century, Immanuel Kant used the concept of telos as a regulative principle in his Critique of Judgment. Teleology was also fundamental to the philosophy of G. W. F. Hegel. 

Contemporary philosophers and scientists are still discussing whether teleological axioms are useful or accurate in proposing modern philosophies and scientific theories. Example of reintroducing of teleology in modern language is notion of attractor. For another instance in 2012, Thomas Nagel, who is not a biologist, proposed a non-Darwinian account of evolution that incorporates impersonal and natural teleological laws to explain the existence of life, consciousness, rationality, and objective value. Regardless, the accuracy can also be considered independently from the usefulness: it is a common experience in pedagogy that a minimum of apparent teleology can be useful in thinking about and explaining Darwinian evolution even if there is no true teleology driving evolution. Thus it is easier to say that evolution "gave" wolves sharp canine teeth because those teeth "serve the purpose of" predation regardless of whether there is an underlying nonteleologic reality in which evolution is not an actor with intentions. In other words, because human cognition and learning often rely on the narrative structure of stories (with actors, goals, and proximal rather than distal causation), some minimal level of teleology might be recognized as useful or at least tolerable for practical purposes even by people who reject its cosmologic accuracy.

Etymology

The word teleology builds on the Greek τέλος, telos (root: τελε-, "end, purpose") and -λογία, logia, "speak of, study of, a branch of learning". The German philosopher Christian von Wolff coined the term (in the Latin form "teleologia") in 1728 in his work Philosophia rationalis, sive logica.

Historical overview

In western philosophy, the term and concept of teleology originated in the writings of Plato and Aristotle. Aristotle's Four Causes give special place to each thing's telos or "final cause." In this, he followed Plato in seeing purpose in both human and sub-human nature.

Platonic

In the Phaedo, Plato through Socrates argues that true explanations for any given physical phenomenon must be teleological. He bemoans those who fail to distinguish between a thing's necessary and sufficient causes, which he identifies respectively as material and final causes (Phaedo 98–99):

Imagine not being able to distinguish the real cause, from that without which the cause would not be able to act, as a cause. It is what the majority appear to do, like people groping in the dark; they call it a cause, thus giving it a name that does not belong to it. That is why one man surrounds the earth with a vortex to make the heavens keep it in place, another makes the air support it like a wide lid. As for their capacity of being in the best place they could be at this very time, this they do not look for, nor do they believe it to have any divine force, but they believe that they will some time discover a stronger and more immortal Atlas to hold everything together more, and they do not believe that the truly good and 'binding' binds and holds them together.

— Plato, Phaedo 99

Plato here argues that while the materials that compose a body are necessary conditions for its moving or acting in a certain way, they nevertheless cannot be the sufficient condition for its moving or acting as it does. For example, (given in Phaedo 98), if Socrates is sitting in an Athenian prison, the elasticity of his tendons is what allows him to be sitting, and so a physical description of his tendons can be listed as necessary conditions or auxiliary causes of his act of sitting (Phaedo 99b; Timaeus 46c9–d4, 69e6). However, these are only necessary conditions of Socrates' sitting. To give a physical description of Socrates' body is to say that Socrates is sitting, but it does not give us any idea why it came to be that he was sitting in the first place. To say why he was sitting and not not sitting, we have to explain what it is about his sitting that is good, for all things brought about (i.e., all products of actions) are brought about because the actor saw some good in them. Thus, to give an explanation of something is to determine what about it is good. Its goodness is its actual cause—its purpose, telos or "reason for which" (Timaeus 27d8–29a).

Aristotelian

Aristotle argued that Democritus was wrong to attempt to reduce all things to mere necessity, because doing so neglects the aim, order, and "final cause", which brings about these necessary conditions:

Democritus, however, neglecting the final cause, reduces to necessity all the operations of nature. Now, they are necessary, it is true, but yet they are for a final cause and for the sake of what is best in each case. Thus nothing prevents the teeth from being formed and being shed in this way; but it is not on account of these causes but on account of the end....

— Aristotle, Generation of Animals V.8, 789a8–b15

In the Physics Aristotle rejected Plato's assumption that the universe was created by an intelligent designer using eternal forms as his model. For Aristotle, natural ends are produced by "natures" (principles of change internal to living things), and natures, Aristotle argued, do not deliberate:

It is absurd to suppose that ends are not present [in nature] because we do not see an agent deliberating.

— Aristotle, Physics 2.8, 199b27-9;

These Platonic and Aristotelian arguments ran counter to those presented earlier by Democritus and later by Lucretius, both of whom were supporters of what is now often called accidentalism:

Nothing in the body is made in order that we may use it. What happens to exist is the cause of its use.

— Lucretius, De rerum natura (On the Nature of Things), IV, 833; cf. 822–56.

Disfavor

Since the Novum Organum of Francis Bacon, teleological explanations in physical science tend to be deliberately avoided in favor of focus on material and efficient explanations. Final and formal causation came to be viewed as false or too subjective. Nonetheless, some disciplines, in particular within evolutionary biology, continue to use language that appears teleological when they describe natural tendencies towards certain end conditions; although some argue that these arguments ought to be, and practicably can be, rephrased in non-teleological forms, others hold that teleological language cannot always be easily expunged from descriptions in the life sciences, at least within the bounds of practical pedagogy.

Economics

A teleology of human aims played a crucial role in the work of Ludwig von Mises especially in the development of his science of praxeology. More specifically he believed that human action, i.e. purposeful behavior, is teleological based on the presupposition that an individual's action is governed or caused by the existence of their chosen ends. Or in other words an individual selects what they believe to be the most appropriate means to achieve a sought after goal or end. Mises however also stressed that teleology with respect to human action was by no means independent of causality as he states "no action can be devised and ventured upon without definite ideas about the relation of cause and effect, teleology presupposes causality"

Modern and postmodern philosophy

Historically, teleology may be identified with the philosophical tradition of Aristotelianism. The rationale of teleology was explored by Immanuel Kant in his Critique of Judgement and, again, made central to speculative philosophy by Hegel and in the various neo-Hegelian schools – proposing a history of our species some consider to be at variance with Darwin, as well as with the dialectical materialism of Karl Marx and Friedrich Engels, and with what is now called analytic philosophy – the point of departure is not so much formal logic and scientific fact but 'identity'. (In Hegel's terminology: 'objective spirit'.) 

Individual human consciousness, in the process of reaching for autonomy and freedom, has no choice but to deal with an obvious reality: the collective identities (such as the multiplicity of world views, ethnic, cultural and national identities) that divide the human race and set (and always have set) different groups in violent conflict with each other. Hegel conceived of the 'totality' of mutually antagonistic world-views and life-forms in history as being 'goal-driven', that is, oriented towards an end-point in history. The 'objective contradiction' of 'subject' and 'object' would eventually 'sublate' into a form of life that leaves violent conflict behind. This goal-oriented, 'teleological' notion of the 'historical process as a whole' is present in a variety of 20th-century authors, although its prominence declined drastically after the Second World War. 

In contrast, teleological based "grand narratives" are eschewed by the postmodern attitude and teleology may be viewed as reductive, exclusionary and harmful to those whose stories are diminished or overlooked.

Against this postmodern position, Alasdair MacIntyre has argued that a narrative understanding of oneself, of one's capacity as an independent reasoner, one's dependence on others and on the social practices and traditions in which one participates, all tend towards an ultimate good of liberation. Social practices may themselves be understood as teleologically oriented to internal goods, for example practices of philosophical and scientific inquiry are teleologically ordered to the elaboration of a true understanding of their objects. MacIntyre's book After Virtue famously dismissed the naturalistic teleology of Aristotle's 'metaphysical biology', but he has cautiously moved from that book's account of a sociological teleology toward an exploration of what remains valid in a more traditional teleological naturalism.

Ethics

Teleology informs the study of ethics.

Business ethics

Business people commonly think in terms of purposeful action as in, for example, management by objectives. Teleological analysis of business ethics leads to consideration of the full range of stakeholders in any business decision, including the management, the staff, the customers, the shareholders, the country, humanity and the environment.

Medical ethics

Teleology provides a moral basis for the professional ethics of medicine, as physicians are generally concerned with outcomes and must therefore know the telos of a given treatment paradigm.

Consequentialism

The broad spectrum of consequentialist ethics, of which utilitarianism is a well-known example, focuses on the end result or consequences, with such principles as utilitarian philosopher John Stuart Mill's "the greatest good for the greatest number", or the Principle of Utility. Hence, this principle is teleological, but in a broader sense than is elsewhere understood in philosophy. In the classical notion, teleology is grounded in the inherent natures of things themselves, whereas in consequentialism, teleology is imposed on nature from outside by the human will. Consequentialist theories justify inherently what most people would call evil acts by their desirable outcomes, if the good of the outcome outweighs the bad of the act. So, for example, a consequentialist theory would say it was acceptable to kill one person in order to save two or more other people. These theories may be summarized by the maxim "the ends can justify the means." 

Consequentialism stands in contrast to the more classical notions of deontological ethics, such as Immanuel Kant's Categorical Imperative, and Aristotle's virtue ethics (although formulations of virtue ethics are also often consequentialist in derivation). In deontological ethics, the goodness or badness of individual acts is primary and a desirable larger goal is insufficient to justify bad acts committed on the way to that goal, even if the bad acts are relatively minor and the goal is major (like telling a small lie to prevent a war and save millions of lives). In requiring all constituent acts to be good, deontological ethics is much more rigid than consequentialism, which varies by circumstances.

Practical ethics are usually a mix of the two. For example, Mill also relies on deontic maxims to guide practical behavior, but they must be justifiable by the principle of utility.

Science

In modern science, explanations that rely on teleology are often, but not always, avoided, either because they are unnecessary or because whether they are true or false is thought to be beyond the ability of human perception and understanding to judge. But using teleology as an explanatory style, in particular within evolutionary biology, is still controversial.

Biology

Apparent teleology is a recurring issue in evolutionary biology, much to the consternation of some writers.

Statements implying that nature has goals, for example where a species is said to do something "in order to" achieve survival, appear teleological, and therefore invalid. Usually, it is possible to rewrite such sentences to avoid the apparent teleology. Some biology courses have incorporated exercises requiring students to rephrase such sentences so that they do not read teleologically. Nevertheless, biologists still frequently write in a way which can be read as implying teleology even if that is not the intention. These issues have recently been discussed by John Reiss. He argues that evolutionary biology can be purged of such teleology by rejecting the analogy of natural selection as a watchmaker; other arguments against this analogy have also been promoted by writers such as Richard Dawkins.

Some authors, like James Lennox, have argued that Darwin was a teleologist, while others like Michael Ghiselin described this claim as a myth promoted by misinterpretations of his discussions and emphasized the distinction between using teleological metaphors and being teleological.

Biologist philosopher Francisco Ayala has argued that all statements about processes can be trivially translated into teleological statements, and vice versa, but that teleological statements are more explanatory and cannot be disposed of. Karen Neander has argued that the modern concept of biological 'function' is dependent upon selection. So, for example, it is not possible to say that anything that simply winks into existence without going through a process of selection has functions. We decide whether an appendage has a function by analysing the process of selection that led to it. Therefore, any talk of functions must be posterior to natural selection and function cannot be defined in the manner advocated by Reiss and Dawkins. Ernst Mayr states that "adaptedness... is an a posteriori result rather than an a priori goal-seeking." Various commentators view the teleological phrases used in modern evolutionary biology as a type of shorthand. For example, S. H. P. Madrell writes that "the proper but cumbersome way of describing change by evolutionary adaptation [may be] substituted by shorter overtly teleological statements" for the sake of saving space, but that this "should not be taken to imply that evolution proceeds by anything other than from mutations arising by chance, with those that impart an advantage being retained by natural selection." J. B. S. Haldane said, "Teleology is like a mistress to a biologist: he cannot live without her but he's unwilling to be seen with her in public."

Selected-effects accounts, like the one Neander suggests, face objections due to their reliance on etiological accounts, which some fields lack the resources to accommodate. Many such sciences, which study the same traits and behaviors regarded by evolutionary biology, still correctly attribute teleological functions without appeal to selection history. Gualtiero Piccinini and Corey J. Maley are a proponent of one such account which focuses instead on goal-contribution. With the objective goals of organisms being survival and inclusive fitness, Piccinini and Maley define teleological functions to be “a stable contribution by a trait (or component, activity, property) of organisms belonging to a biological population to an objective goal of those organisms.”

Cybernetics

Julian Bigelow, Arturo Rosenblueth, and Norbert Wiener have conceived of feedback mechanisms as lending a teleology to machinery. Wiener, a mathematician, coined the term 'cybernetics' to denote the study of "teleological mechanisms." Cybernetics is the study of the communication and control of regulatory feedback both in living beings and machines, and in combinations of the two. In the cybernetic classification presented in "Behavior, Purpose and Teleology", teleology is feedback controlled purpose.

The classification system underlying cybernetics was criticized by Frank Honywill George, who cited the need for an external observability to the purposeful behavior in order to establish and validate the goal-seeking behavior. In this view, the purpose of observing and observed systems is respectively distinguished by the system's subjective autonomy and objective control.

Collective animal behavior

From Wikipedia, the free encyclopedia

Starling flock at sunset in Denmark

 

Collective animal behavior is a form of social behavior involving the coordinated behavior of large groups of similar animals as well as emergent properties of these groups. This can include the costs and benefits of group membership, the transfer of information across the group, the group decision-making process, and group locomotion and synchronization. Studying the principles of collective animal behavior has relevance to human engineering problems through the philosophy of biomimetics. For instance, determining the rules by which an individual animal navigates relative to its neighbors in a group can lead to advances in the deployment and control of groups of swimming or flying micro-robots such as UAVs (Unmanned Aerial Vehicles).

Examples

Examples of collective animal behavior include:

• Flocking birds
• Herding ungulates
• Shoaling and schooling fish
• Schooling Antarctic krill
• Pods of dolphins
• Marching locusts
• Nest building ants

Proposed functions

Many functions of animal aggregations have been proposed. These proposed functions may be grouped into the four following categories: social and genetic, anti-predator, enhanced foraging, and increased locomotion efficiency.

Social interaction

Support for the social and genetic function of aggregations, especially those formed by fish, can be seen in several aspects of their behavior. For instance, experiments have shown that individual fish removed from a school will have a higher respiratory rate than those found in the school. This effect has been partly attributed to stress, although hydrodynamic factors were considered more important in this particular study. The calming effect of being with conspecifics may thus provide a social motivation for remaining in an aggregation. Herring, for instance, will become very agitated if they are isolated from conspecifics. Fish schools have also been proposed to serve a reproductive function since they provide increased access to potential mates.

Protection from predators

School of goldband fusiliers

 

Several anti-predator functions of animal aggregations have been proposed. One potential method by which fish schools or bird flocks may thwart predators is the ‘predator confusion effect’ proposed and demonstrated by Milinski and Heller (1978). This theory is based on the idea that it becomes difficult for predators to pick out individual prey from groups because the many moving targets create a sensory overload of the predator's visual channel. Milinski and Heller's findings have been corroborated both in experiment and computer simulations.

A second potential anti-predator effect of animal aggregations is the "many eyes" hypothesis. This theory states that as the size of the group increases, the task of scanning the environment for predators can be spread out over many individuals. Not only does this mass collaboration presumably provide a higher level of vigilance, it could also allow more time for individual feeding.

A third hypothesis for an anti-predatory effect of animal aggregation is the "encounter dilution" effect. Hamilton, for instance, proposed that the aggregation of animals was due to a "selfish" avoidance of a predator and was thus a form of cover-seeking. Another formulation of the theory was given by Turner and Pitcher and was viewed as a combination of detection and attack probabilities. In the detection component of the theory, it was suggested that potential prey might benefit by living together since a predator is less likely to chance upon a single group than a scattered distribution. In the attack component, it was thought that an attacking predator is less likely to eat a particular animal when a greater number of individuals are present. In sum, an individual has an advantage if it is in the larger of two groups, assuming that the probability of detection and attack does not increase disproportionately with the size of the group.

Enhanced foraging

A third proposed benefit of animal groups is that of enhanced foraging. This ability was demonstrated by Pitcher and others in their study of foraging behavior in shoaling cyprinids. In this study, the time it took for groups of minnows and goldfish to find a patch of food was quantified. The number of fishes in the groups was varied, and a statistically significant decrease in the amount of time necessary for larger groups to find food was established. Further support for an enhanced foraging capability of schools is seen in the structure of schools of predatory fish. Partridge and others analyzed the school structure of Atlantic bluefin tuna from aerial photographs and found that the school assumed a parabolic shape, a fact that was suggestive of cooperative hunting in this species (Partridge et al., 1983).

Increased locomotion efficiency

This theory states that groups of animals moving in a fluid environment may save energy when swimming or flying together, much in the way that bicyclists may draft one another in a peloton. Geese flying in a Vee formation are also thought to save energy by flying in the updraft of the wingtip vortex generated by the previous animal in the formation. Ducklings have also been shown to save energy by swimming in a line. Increased efficiencies in swimming in groups have also been proposed for schools of fish and Antarctic krill.

Group structure

The structure of large animal groups has been difficult to study because of the large number of animals involved. The experimental approach is therefore often complemented by mathematical modeling of animal aggregations.

Experimental approach

Experiments investigating the structure of animal aggregations seek to determine the 3D position of each animal within a volume at each point in time. It is important to know the internal structure of the group because that structure can be related to the proposed motivations for animal grouping. This capability requires the use of multiple cameras trained on the same volume in space, a technique known as stereophotogrammetry. When hundreds or thousands of animals occupy the study volume, it becomes difficult to identify each one. In addition, animals may block one another in the camera views, a problem known as occlusion. Once the location of each animal at each point in time is known, various parameters describing the animal group can be extracted. 

These parameters include:

Density: The density of an animal aggregation is the number of animals divided by the volume (or area) occupied by the aggregation. Density may not be a constant throughout the group. For instance, starling flocks have been shown to maintain higher densities on the edges than in the middle of the flock, a feature that is presumably related to defense from predators.

Polarity: The group polarity describes if the group animals are all pointing in the same direction or not. In order to determine this parameter, the average orientation of all animals in the group is determined. For each animal, the angular difference between its orientation and the group orientation is then found. The group polarity is then the average of these differences (Viscido 2004).

Nearest Neighbor Distance: The nearest neighbor distance (NND) describes the distance between the centroid of one animal (the focal animal) and the centroid of the animal nearest to the focal animal. This parameter can be found for each animal in an aggregation and then averaged. Care must be taken to account for the animals located at the edge of an animal aggregation. These animals have no neighbor in one direction. 

Nearest Neighbor Position: In a polar coordinate system, the nearest neighbor position describes the angle and distance of the nearest neighbor to a focal animal. 

Packing Fraction: Packing fraction is a parameter borrowed from physics to define the organization (or state i.e. solid, liquid, or gas) of 3D animal groups. It is an alternative measure to density. In this parameter, the aggregation is idealized as an ensemble of solid spheres, with each animal at the center of a sphere. The packing fraction is defined as the ratio of the total volume occupied by all individual spheres divided by the global volume of the aggregation (Cavagna 2008). Values range from zero to one, where a small packing fraction represents a dilute system like a gas. Cavagna found that the packing fraction for groups of starlings was 0.012.

Integrated Conditional Density: This parameter measures the density at various length scales and therefore describes the homogeneity of density throughout an animal group.

Pair Distribution Function: This parameter is usually used in physics to characterize the degree of spatial order in a system of particles. It also describes the density, but this measures describes the density at a distance away from a given point. Cavagna et al. found that flocks of starlings exhibited more structure than a gas but less than a liquid.

Modeling approach

The simplest mathematical models of animal aggregations generally instruct the individual animals to follow three rules:

1. Move in the same direction as your neighbor
2. Remain close to your neighbors
3. Avoid collisions with your neighbors

A diagram illustrating the difference between 'metric distance' and 'topological distance' in reference to fish schools

 

An example of such a simulation is the Boids program created by Craig Reynolds in 1986. Another is the Self Propelled Particle model. Many current models use variations on these rules. For instance, many models implement these three rules through layered zones around each animal. In the zone of repulsion very close to the animal, the focal animal will seek to distance itself from its neighbors in order to avoid a collision. In the slightly further away zone of alignment, a focal animal will seek to align its direction of motion with its neighbors. In the outmost zone of attraction, which extends as far away from the focal animal as it is able to sense, the focal animal will seeks to move towards a neighbor. The shape of these zones will necessarily be affected by the sensory capabilities of the animal. For example, the visual field of a bird does not extend behind its body. Fish, on the other hand, rely on both vision and on hydrodynamic signals relayed through its lateral line. Antarctic krill rely on vision and on hydrodynamic signals relayed through its antennae. 

Recent studies of starling flocks have shown, however, that each bird modifies its position relative to the six or seven animals directly surrounding it, no matter how close or how far away those animals are. Interactions between flocking starlings are thus based on a topological rule rather than a metric rule. It remains to be seen whether the same rule can be applied to other animals. Another recent study, based on an analysis of high speed camera footage of flocks above Rome and assuming minimal behavioural rules, has convincingly simulated a number of aspects of flock behaviour.

Collective decision making

Aggregations of animals are faced with decisions which they must make if they are to remain together. For a school of fish, an example of a typical decision might be which direction to swim when confronted by a predator. Social insects such as ants and bees must collectively decide where to build a new nest. A herd of elephants must decide when and where to migrate. How are these decisions made? Do stronger or more experienced 'leaders' exert more influence than other group members, or does the group make a decision by consensus? The answer probably depends on the species. While the role of a leading matriarch in an elephant herd is well known, studies have shown that some animal species use a consensus approach in their collective decision-making process. 

A recent investigation showed that small groups of fish used consensus decision-making when deciding which fish model to follow. The fish did this by a simple quorum rule such that individuals watched the decisions of others before making their own decisions. This technique generally resulted in the 'correct' decision but occasionally cascaded into the 'incorrect' decision. In addition, as the group size increased, the fish made more accurate decisions in following the more attractive fish model. Consensus decision-making, a form of collective intelligence, thus effectively uses information from multiple sources to generally reach the correct conclusion. 

Some simulations of collective decision-making use the Condorcet method to model the way groups of animals come to consensus.

Anatomical terminology

From Wikipedia, the free encyclopedia

 

Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors.

 

Anatomical terminology uses many unique terms, suffixes, 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. Also, since these anatomical terms are not used in everyday conversation, their meanings are less likely to change, and less likely 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; and could be on the palm-side or back-side of the arm. By using precise anatomical terminology such ambiguity is eliminated.

An international standard for anatomical terminology, Terminologia Anatomica has been created.

Word formation

Anatomical terminology has quite regular morphology, the same prefixes and suffixes are used to add meanings to different roots. The root of a term often 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, and 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 (skull), facies (face), frons (forehead), oculus (eye area), auris (ear), bucca (cheek), nasus (nose), oris (mouth), and mentum (chin). The neck area is called the cervix or 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, and is particularly used when describing the skull. Similarly, different terminology is often 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 also used to describe the movement and actions of the hands and feet, and other structures such as the eye.

History

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, teaching 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 descriptive and functional. Basically, it covers the gross anatomy and the microscopic (histology and cytology) of living beings. It involves both development anatomy (embryology) and the anatomy of the adult. It also includes comparative anatomy between different species. The vocabulary is extensive, varied and complex, and requires a systematic presentation. 

Within the international field, a group of experts reviews, analyzes and discusses the morphological terms of the structures of the human body, forming today's Terminology Committee (FICAT) from the International Federation of Associations of Anatomists (IFAA). It deals with the anatomical, histological and embryologic terminology. In the Latin American field, there are meetings called Iberian Latin American Symposium Terminology (SILAT), where a group of experts of the Pan American Association of Anatomy (PAA) that speak Spanish and Portuguese, disseminates and studies the international morphological terminology. 

The current international standard for human anatomical terminology is based on the Terminologia Anatomica (TA). It was developed by the Federative Committee on Anatomical Terminology (FCAT) and the International Federation of Associations of Anatomists (IFAA) and was released in 1998. It supersedes the previous standard, Nomina Anatomica. Terminologia Anatomica contains terminology for about 7500 human gross (macroscopic) anatomical structures. For microanatomy, known as histology, a similar standard exists in Terminologia Histologica, and for embryology, the study of development, a standard exists in Terminologia Embryologica. These standards specify generally accepted names that can be used to refer to histological and embryological structures in journal articles, textbooks, 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.

Recently, the Terminologia Anatomica has been perceived with a considerable criticism regarding its content including coverage, grammar and spelling mistakes, inconsistencies, and errors.

Location

Anatomical terminology is often 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 position

The anatomical position, with terms of relative location noted.

 

Anatomical terms used to describe location are based on a body positioned in what is called the standard anatomical position. This position is one in which a person is standing, feet apace, with palms forward and thumbs facing outwards. Just as maps are normally oriented with north at the top, the standard body "map," or anatomical position, is that of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side, and the palms of the hands face forward.

Using the standard anatomical position reduces confusion. It means that regardless of the position of a body, the position of structures within it can be described without ambiguity.

Regions

The human body is shown in anatomical position in an anterior view and a posterior view. The regions of the body are labeled in boldface.

 

In terms of anatomy, the body is divided into regions. In the front, the trunk is referred to as the "thorax" and "abdomen". The back as a general area is the dorsum or dorsal area, and the lower back is the lumbus or lumbar region. The shoulder blades are the scapular area and the breastbone is the sternal region. The abdominal area is the region between the chest and the pelvis. The breast is also called the mammary region, the armpit as the axilla and axillary, and the navel as the umbilicus and umbilical. The pelvis is the lower torso, between the abdomen and the thighs. The groin, where the thigh joins the trunk, are the inguen and inguinal area.

The entire arm is referred to as the brachium and brachial, the front of the elbow as the antecubitis and antecubital, the back of the elbow as the olecranon or olecranal, the forearm as the antebrachium and antebrachial, the wrist as the carpus and carpal area, the hand as the manus and manual, the palm as the palma and palmar, the thumb as the pollex, and the fingers as the digits, phalanges, and phalangeal. The buttocks are the gluteus or gluteal region and the pubic area is the pubis. 

Anatomists divide the lower limb into the thigh (the part of the limb between the hip and the knee) and the leg (which refers only to the area of the limb between the knee and the ankle). The thigh is the femur and the femoral region. The kneecap is the patella and patellar while the back of the knee is the popliteus and popliteal area. The leg (between the knee and the ankle) is the crus and crural area, the lateral aspect of the leg is the peroneal area, and the calf is the sura and sural region. The ankle is the tarsus and tarsal, and the heel is the calcaneus or calcaneal. The foot is the pes and pedal region, and the sole of the foot the planta and plantar. As with the fingers, the toes are also called the digits, phalanges, and phalangeal area. The big toe is referred to as the hallux.

Abdomen

Abdominal regions are used for example to localize pain.

To promote clear communication, for instance about the location of a patient’s abdominal pain or a suspicious mass, the abdominal cavity can be divided into either nine regions or four quadrants.

Quadrants

The abdomen may be divided into four quadrants, more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersect at the patient’s umbilicus (navel). The right upper quadrant (RUQ) includes the lower right ribs, right side of the liver, and right side of the transverse colon. The left upper quadrant (LUQ) includes the lower left ribs, stomach, spleen, and upper left area of the transverse colon. The right lower quadrant (RLQ) includes the right half of the small intestines, ascending colon, right pelvic bone and upper right area of the bladder. The left lower quadrant (LLQ) contains the left half of the small intestine and left pelvic bone.

Regions

The more detailed regional approach subdivides the cavity into nine regions, with two vertical and two horizontal lines drawn according to landmark structures. The vertical; or midclavicular lines, are drawn as if dropped from the midpoint of each clavicle. The superior horizontal line is the subcostal line, drawn immediately inferior to the ribs. The inferior horizontal line is called the intertubercular line, and is to cross the iliac tubercles, found at the superior aspect of the pelvis. The upper right square is the right hypochondriac region and contains the base of the right ribs. The upper left square is the left hypochondriac region and contains the base of the left ribs. 

The epigastric region is the upper central square and contains the bottom edge of the liver as well as the upper areas of the stomach. The diaphragm curves like an upside down U over these three regions. The central right region is called the right lumbar region and contains the ascending colon and the right edge of the small intestines. The central square contains the transverse colon and the upper regions of the small intestines. The left lumbar region contains the left edge of the transverse colon and the left edge of the small intestine. The lower right square is the right iliac region and contains the right pelvic bones and the ascending colon. The lower left square is the left iliac region and contains the left pelvic bone and the lower left regions of the small intestine. The lower central square contains the bottom of the pubic bones, upper regions of the bladder and the lower region of the small intestine.

Standard terms

When anatomists refer to the right and left of the body, it is in reference to the right and left of the subject, not the right and left of the observer. When observing a body in the anatomical position, the left of the body is on the observer’s right, and vice versa. 

These standardized terms avoid confusion. Examples of terms include:

• Anterior and posterior, which describe structures at the front (anterior) and back (posterior) of the body. For example, the toes are anterior to the heel, and the popliteus is posterior to the patella.
• Superior and inferior, which describe a position above (superior) or below (inferior) another part of the body. For example, the orbits are superior to the oris, and the pelvis is inferior to the abdomen.
• Proximal and distal, which describe a position that is closer (proximal) or further (distal) from the trunk of the body. For example, the shoulder is proximal to the arm, and the foot is distal to the knee.
• Superficial and deep, which describe structures that are closer to (superficial) or further from (deep) the surface of the body. For example, the skin is superficial to the bones, and the brain is deep to the skull. Sometimes profound is used synonymously with deep.
• Medial and lateral, which describe a position that is closer to (medial) or further from (lateral) the midline of the body. For example, the nose is medial to the eyes, and the thumb is lateral to the other fingers.
• Ventral and dorsal, which describe structures derived from the front (ventral) and back (dorsal) of the embryo, before limb rotation.
• Cranial and caudal, which describe structures close to the top of the skull (cranial), and towards the bottom of the body (caudal).
• Occasionally, sinister for left, and dexter for right are used.
• Paired, referring to a structure that is present on both sides of the body. For example, the hands are paired structures.

Axes

Each locational term above can define the direction of a vector, and pairs of them can define axes, that is, lines of orientation. For example, blood can be said to flow in a proximal or distal direction, and anteroposterior, mediolateral, and inferosuperior axes are lines along which the body extends, like the X, Y, and Z axes of a Cartesian coordinate system. An axis can be projected to a corresponding plane.

Planes

The three anatomical planes of the body: the sagittal, transverse (or horizontal), frontal planes

 

Anatomy is often described in planes, referring to two-dimensional sections of the body. A section is a two-dimensional surface of a three-dimensional structure that has been cut. A plane is an imaginary two-dimensional surface that passes through the body. Three planes are commonly referred to in anatomy and medicine:

• The sagittal plane is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane, or less commonly a longitudinal section.
• The frontal plane is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane, following Latin corona, which means "crown".
• The transverse plane is the plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.

Functional state

Anatomical terms may be used to describe the functional state of an organ:^{[citation needed]}

• Anastomoses refers to the connection between two structures previously branched out, such as blood vessels or leaf veins.
• Patent, meaning a structure such as an artery or vein that abnormally remains open, such as a patent ductus arteriosus, referring to the ductus arteriosus which normally becomes ligamentum arteriosum within three weeks of birth. Something that is patent may also refer to a channel such as a blood vessel, section of bowel, collecting system or duct that is not occluded and remains open to free flow. Such obstructions may include a calculus (i.e. a kidney stone or gallstone), plaque (like that encountered in vital arteries such as coronary arteries and cerebral arteries), or another unspecified obstruction, such as a mass or bowel obstruction.
• A plexus refers to a net-like arrangement of a nerve.

Anatomical variation

The term anatomical variation is used to refer to a difference in anatomical structures that is not regarded as a disease. Many structures vary slightly between people, for example muscles that attach in slightly different places. For example, the presence or absence of the palmaris longus tendon. Anatomical variation is unlike congenital anomalies, which are considered a disorder.

Movement

Joints, especially synovial joints allow the body a tremendous range of movements. Each movement at a synovial joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. The type of movement that can be produced at a synovial joint is determined by its structural type.

Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward.

General motion

Terms describing motion in general include:

• Flexion and extension, which refer to a movement that decreases (flexion) or increases (extension) the angle between body parts. For example, when standing up, the knees are extended.
• Abduction and adduction refers to a motion that pulls a structure away from (abduction) or towards (adduction) the midline of the body or limb. For example, a star jump requires the legs to be abducted.
• Internal rotation (or medial rotation) and external rotation (or lateral rotation) refers to rotation towards (internal) or away from (external) the center of the body. For example, the Lotus position posture in yoga requires the legs to be externally rotated.
• Elevation and depression refer to movement in a superior (elevation) or inferior (depression) direction. Primarily refers to movements involving the scapula and mandible.

Special motions of the hands and feet

These terms refer to movements that are regarded as unique to the hands and feet:

• Dorsiflexion and plantarflexion refers to flexion (dorsiflexion) or extension of the foot at the ankle. For example, plantarflexion occurs when pressing the brake pedal of a car.
• Palmarflexion and dorsiflexion refer to movement of the flexion (palmarflexion) or extension (dorsiflexion) of the hand at the wrist. For example, prayer is often conducted with the hands dorsiflexed.
• Pronation and supination refer to rotation of the forearm or foot so that in the anatomical position the palm or sole is facing anteriorly (supination) or posteriorly (pronation) . For example, if a person makes a "thumbs up" gesture, supination will cause the thumb to point away from the body midline and the fingers and plam to be upwards, while pronation will cause the thumb to point towards the body midline with the back of the hand upwards.
• Eversion and inversion refer to movements that tilt the sole of the foot away from (eversion) or towards (inversion) the midline of the body.

Muscles

The biceps brachii flex the lower arm. The brachioradialis, in the forearm, and brachialis, located deep to the biceps in the upper arm, are both synergists that aid in this motion.

 

Muscle action that moves the axial skeleton work over a joint with an origin and insertion of the muscle on respective side. The insertion is on the bone deemed to move towards the origin during muscle contraction. Muscles are often present that engage in several actions of the joint; able to perform for example both flexion and extension of the forearm as in the biceps and triceps respectively. This is not only to be able to revert actions of muscles, but also brings on stability of the actions though muscle coactivation.

Agonist and antagonist muscles

The muscle performing an action is the agonist, while the muscle which contraction brings about an opposite action is the antagonist. For example, an extension of the lower arm is performed by the triceps as the agonist and the biceps as the antagonist (which contraction will perform flexion over the same joint). Muscles that work together to perform the same action are called synergists. In the above example synergists to the biceps can be the brachioradialis and the brachialis muscle.

Skeletal and smooth muscle

The skeletal muscles of the body typically come in seven different general shapes. This figure shows the human body with the major muscle groups labeled.

 

The gross anatomy of a muscle is the most important indicator of its role in the body. One particularly important aspect of gross anatomy of muscles is pennation or lack thereof. In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion. In pennate muscles, the individual fibers are oriented at an angle relative to the line of action, attaching to the origin and insertion tendons at each end. Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris.

Skeletal muscle is arranged in discrete muscles, an example of which is the biceps brachii. The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the tendons. In turn, the tendons connect to the periosteum layer surrounding the bones, permitting the transfer of force from the muscles to the skeleton. Together, these fibrous layers, along with tendons and ligaments, constitute the deep fascia of the body.

Joints

Movement is not limited to only synovial joints, although they allow for most freedom. Muscles also run over symphysis, which allow for movement in for example the vertebral column by compression of the intervertebral discs. Additionally, synovial joints can be divided into different types, depending on their axis of movement.

Membranes

Serous membrane

 

A serous membrane (also referred to as a serosa) is a thin membrane that covers the walls of organs in the thoracic and abdominal cavities. The serous membranes have two layers; parietal and visceral, surrounding a fluid filled space. The visceral layer of the membrane covers the organ (the viscera), and the parietal layer lines the walls of the body cavity (pariet- refers to a cavity wall). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity. For example, the pericardium is the serous cavity which surrounds the heart.

• Visceral and parietal describe structures that relate to an organ (visceral), or the wall of the cavity that the organ is in (parietal). For example, the parietal peritoneum surrounds the abdominal cavity.

Additional images

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  Older set of terminology shown in Parts of the Human Body: Posterior and Anterior View from the 1933 edition of Sir Henry Morris' Human Anatomy.
  
  
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  Labels of human body features displayed on images of actual human bodies, from which body hair and male facial hair has been removed.