In sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons.

Figure 1: Animals often change position with respect to their environment.

Two major problems arise with common usage, however. First, they tend to be language-specific, requiring translation into equivalent, or almost-equivalent, terms in other languages. They are not universal terms that may be readily understood by zoologists speaking other languages. Differences in terminology remain a problem that, to some extent, still separates the fields of zoological anatomy (sometimes called zootomy) and human (medical) anatomy. Image File history File links Size of this preview: 800 × 584 pixels Full resolution (900 × 657 pixel, file size: 277 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Image File history File links Size of this preview: 800 × 584 pixels Full resolution (900 × 657 pixel, file size: 277 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Zootomy is a contraction of zoological and anatomy and refers to the dissection of animals as opposed to that of plants (phytotomy) See also: Androtomy, zootomical terms for location, Cat anatomy La Anatomía comparada estudia diversas especies. ... List of bones of the human skeleton Human anatomy is primarily the scientific study of the morphology of the adult human body. ...

The second, and larger, problem is caused by the very nature of animals. Most animals are capable of moving relative to their environment (see Fig. 1). So while "up" might refer to the top of someone's head when they are standing upright, the same term ("up") would describe their belly while they are lying down.

Therefore, standardized anatomical (and zootomical) terms of location have been developed, usually based on Latin words, to enable all biological and medical scientists to precisely delineate and communicate information about animal (including human) bodies and their component organs. Latin was the language originally spoken in the region around Rome called Latium. ...

Standard anatomical position

Because animals can change position with respect to their environment, and because any appendages (arms, legs, tentacles, etc...) can change position with respect to the main body, it is important that any positional descriptive terms refer to the organism when it is in its standard anatomical position. The word Animals when used alone has several possible meanings in the English language. ... A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ... Life on Earth redirects here. ...

Thus, and very importantly, all descriptions are with respect to the organism in its standard anatomical position, even when the organism in question has appendages in another position. For example, see Fig. 8, where the tentacles are curved, and therefore not in anatomical position. However, a straight position is assumed when describing the proximo-distal axis. This helps avoid confusion in terminology when referring to the same organism in different postures.

Invertebrate and vertebrate zootomy

There is no formal definition of standard anatomical position used in most zoology. However, the position can be loosely defined as that position in which the organism will usually be found when at rest. Thus, for most invertebrates, this would be the position in which they are normally found when not feeding, hiding, actively moving, and so on (see Figs. 6–9, below), and any appendages are straight. Zoology (from Greek: ζῴον, zoion, animal; and λόγος, logos, knowledge) is the biological discipline which involves the study of animals. ... Invertebrate is a term coined by Chevalier de Lamarck to describe any animal without a backbone or vertebra, like insects, squids and worms. ... A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ...

For bilaterally-symmetrical organisms, such vertebrates or some invertebrates, this can be refined to include that the organisms are standing erect in a normal posture, and looking forward.^[1] (For example, see Figs. 2–4, below.) In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ...

Medical (human) anatomy

Unlike the situation in zootomy, standard anatomical position is rigidly defined for human anatomy. As with other vertebrates, the human body is standing erect and at rest. Unlike the situation in other vertebrates, the limbs (arms and legs) are placed in unnatural positions reminiscent of the supine position imposed on cadavers during autopsy. Therefore, the body has its feet together (or slightly separated), and its arms are rotated outward so that the palms are forward, and the thumbs are pointed away from the body (forearms supine). As well, the arms are usually moved slightly out from the body, so that the hands do not touch the sides.^[2][3] The positions of the limbs (and the arms in particular) have important implications for directional terms in those appendages. The supine position is a position of the body; lying down with the face up, as opposed to the prone position, which is face down. ... With regard to living things, a body is the integral physical material of an individual, and contrasts with soul, personality and behavior. ... For other uses, see Hand (disambiguation). ... Missing image Thumbs up In human anatomy, the thumb is the first digit on a hand. ...

Skull

In humans, the anatomical position of the skull has been agreed by international convention to be the Frankfurt plane, a position where the lower margins of the orbits and the upper margins of the ear canals all lie in the same horizontal plane. This is a good approximation to the position where the subject is standing upright and facing forwards. For other uses of Skull, see Skull (disambiguation). ... The Frankfurt plane (also called the auriculo-orbital plane) was established at the World Congress on Anthropology in Frankfurt, Germany in 1884, and decreed as the anatomical position of the human skull. ... In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. ... The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. ...

Directional terms

Ultimately, the bodies we are most familiar with are vertebrate bodies similar to our own. All vertebrates (including humans) have the same basic body plan (or bauplan) — they are bilaterally symmetrical. That is, they have mirror-image left and right halves if divided down the centre.^[4][5][6][7] 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 (invertebrate) organisms as well. Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... It has been suggested that this article or section be merged into body plan. ... In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ... Invertebrate is an English word that describes any animal without a spinal column. ...

Vertebrate directional terms

To begin, distinct, polar-opposite ends of the organism are chosen. By definition, each pair of opposite points defines an axis. In a bilaterally-symmetrical organism, there are 6 polar opposite points, giving three axes that intersect at right angles — the x, y, and z axes familiar from three-dimensional geometry. Life on Earth redirects here. ...

Figure 2: Anatomical directions and defined axes in a vertebrate

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Anterior and posterior

The most obvious end-points are the "nose" and "tail" (see Fig. 2). Anatomically, the nose is referred to as the anterior end (Latin ante; before). In organisms like vertebrates, that have distinct heads, the anterior end is sometimes referred to as the rostral end (Latin rostrum; beak), the cranial end (Greek kranion; skull), or the cephalic end (Greek kephalē; head).^[8][9][10] For reasons of broader applicability, especially in organisms without distinct heads (many invertebrates), "anterior" is usually preferred.^[11][12][13] Anterior is a five piece Melodic Death Metal band from Tredegar South Wales. ... Latin was the language originally spoken in the region around Rome called Latium. ... Invertebrate is a term coined by Chevalier de Lamarck to describe any animal without a backbone or vertebra, like insects, squids and worms. ...

The polar opposite to the anterior end is the posterior end (Latin post; after). Another term for posterior is caudal (Latin caudum; tail) — a term which strictly applies only to vertebrates, and therefore less preferred.^[14][15][16] The English word POSTERIOR is identical to the original Latin adjective, and has two different uses : as an ADJECTIVE, it indicates that someone or something is behind another, either spatially or chronologically it also became a SUBSTANTIVE, indicating the rear-end, especially of a person, i. ... Latin was the language originally spoken in the region around Rome called Latium. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ...

By drawing a line connecting these two points, we define the anteroposterior axis (sometimes written antero-posterior). Less-used synonyms would be rostrocaudal or cephalocaudal axes (see Table 1). For brevity, the term anteroposterior is often abbreviated to read AP (or A-P) axis. As well as defining the anteroposterior axis, the terms "anterior" and "posterior" also define relative positions along the axis. Thus, in the fish in Fig. 2, the gill openings are posterior relative to the eyes, but anterior to the tail.

This article does not cite any references or sources. ... Zoology (from Greek: ζῴον, zoion, animal; and λόγος, logos, knowledge) is the biological discipline which involves the study of animals. ... Look up appendage in Wiktionary, the free dictionary. ...

Dorsal and ventral

The next most obvious end-points are the back and belly. These are termed the dorsal end (Latin dorsum; back) and the ventral end (Latin venter; abdomen), respectively. By connecting the outermost points the dorsoventral axis is formed (sometimes hyphenated: dorso-ventral). This is commonly abbreviated to DV (or D-V) axis. The DV axis, by definition, is perpendicular (at right angles to) the AP axis at all times (see below). In anatomy, the dorsum is the upper or back side of an animal, as opposed to the ventrum. ... For the human abdomen, see human abdomen. ...

As with anteroposterior, the terms "dorsal" and "ventral" are also used to describe relative positions along the dorsoventral axis. Thus, the pectoral fins are dorsal to the anal fin, but ventral to the dorsal fin in Fig. 2. (Note that these fins are not aligned anteroposteriorly, either — the dorsal fin being posterior to the pectoral, and anterior to the anal fins, respectively.) Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than does air. ... Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than does air. ... Dorsal fin of an orca A dorsal fin is a fin located on the backs of fishes, whales, dolphins, and porpoises, as well as the (extinct) ichthyosaurs. ...

Left and right (lateral), and medial

The last axis, by geometric definition, must be at right angles to both the AP and DV axes. Obviously, the left side and right side of the organism are the outermost points between the two "sides" of the organism. When connected, these points form the left-right axis (commonly abbreviated to LR (or L-R) axis. Properly, this is called the dextro-sinistral (or, more uncommonly, the sinistro-dextral) axis, from the Latin dexter (right) and sinister (left). It is important to note that the "left" and "right" sides are the sides of the organism, and not those of the observer. For other uses, see Geometry (disambiguation). ... Latin was the language originally spoken in the region around Rome called Latium. ...

In practice, and contradictory to the practice with other anatomical terms of location, the vernacular "left-right" is preferentially used in English and some other languages. This is likely due to the adoption of the Latin "sinister" to mean "evil" in English^[17] and other languages (e.g. sinistre in French has the same connotation^[18]). Look up Vernacular in Wiktionary, the free dictionary. ... For other uses, see Evil (disambiguation). ...

As with the other directions, the terms can be used as relative terms, to describe locations along the left-right axis. Thus, in Fig. 2 the dorsal fin is right of the left pectoral fin, but is left of the right eye. However, as left and right sides are mirror images, usage like this tends to be somewhat confusing, as structures are duplicated on both sides (i.e. above there is both a right eye and a left eye, forcing one to specify which is used as a reference). Dorsal fin of an orca A dorsal fin is a fin located on the backs of fishes, whales, dolphins, and porpoises, as well as the (extinct) ichthyosaurs. ... Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than does air. ... For other uses, see Eye (disambiguation). ... A mirror image is a mirror based duplicate of a single image. ...

To counter this clumsiness of usage, the directional term lateral (Latin lateralis; "to the side") is used as a modifier for both sides, yielding the left lateral and right lateral sides. As an opposite to lateral, the term medial (Latin medius; "middle") is used to define a point in the centre of the organism (where the left-right axis intersects the midsagittal plane — see below). Thus, rather than "left-right" axis and its inherent clumsiness of usage, the term mediolateral (also sometimes hyphenated medio-lateral) axis is frequently used. Sometimes this is abbreviated to ML (or M-L) axis.^[19][20][21] Properly, the ML axis is a half axis; practically, its usage is less clumsy and less linguistically biased than "left-right". The terms may still be used relatively to describe locations along the LR axis. Thus, in Fig. 2 the gills are medial to the operculum, but lateral to the heart. Latin was the language originally spoken in the region around Rome called Latium. ... Latin was the language originally spoken in the region around Rome called Latium. ... The midsagittal plane divides the body into left and right halves down the center of the body, along the spine and navel and between the legs. ... In aquatic organisms, gills are a respiratory organ for the extraction of oxygen from water and for the excretion of carbon dioxide. ... The operculum in fish is the hard bony flap covering and protecting the gills of Bony fish. ... The heart and lungs, from an older edition of Grays Anatomy. ...

The usage "mediolateral" is strictly used to describe relative position along the left-right axis, to avoid confusion with the terms "superficial" and "deep" (see below).

Sources of confusion

Figure 3: Directional axes in the tetrapod vertebrate Equus caballus (a horse). The axis between anterior and posterior is the AP axis, and between the dorsal and ventral is the D-V axis. (Left-right axis not shown; image shows the right side of the organism.)

Together, the AP, DV and LR (or ML) axes allow for precise three-dimensional descriptions of location within any bilaterally-symmetrical organism, whether vertebrate or invertebrate. In practice, the terms can cause some confusion when, unlike the fish shown in Fig. 2, the organism in question is not strictly linear in form (see Figs. 3 and 4). For example, the AP axis in Fig. 3 does not appear to be at right angles to the DV axis. Rather, it is a depiction of the approximate average AP axis, when all body segments are included. Image File history File links Size of this preview: 800 × 579 pixelsFull resolution (2931 × 2120 pixel, file size: 909 KB, MIME type: image/jpeg) Esseh 08:49, 18 April 2007 (UTC) File links The following pages on the English Wikipedia link to this file (pages on other projects are not... Image File history File links Size of this preview: 800 × 579 pixelsFull resolution (2931 × 2120 pixel, file size: 909 KB, MIME type: image/jpeg) Esseh 08:49, 18 April 2007 (UTC) File links The following pages on the English Wikipedia link to this file (pages on other projects are not... Groups See text. ... This article does not cite any references or sources. ... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. ... In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ... This article does not cite any references or sources. ... Invertebrate is an English word that describes any animal without a spinal column. ...

Figure 4: Different directional AP axes in three body segments of a horse). Axis (A) (in red) shows the AP axis of the tail, (B) shows the AP axis of the neck, and (C) shows the AP axis of the head.

When considering any one segment, the dorsoventral axis is perpendicular to the AP axis. Thus, in Fig. 4, the DV axis of the tail would run from the "back" of the tail (posterior end of the trunk), to the "underside" of the tail (near the legs) — nearly parallel to the AP axis of the main body. Image File history File links Size of this preview: 800 × 579 pixelsFull resolution (2931 × 2120 pixel, file size: 1. ... Image File history File links Size of this preview: 800 × 579 pixelsFull resolution (2931 × 2120 pixel, file size: 1. ... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. ...

As a general rule of thumb, if the body is included in consideration, the AP axis of the main body would be used, as would the DV and ML axes perpendicular to it. However, if considering only one segment, the AP axis would shift to reflect the axes shown in Fig. 4, with the DV and ML axes shifting correspondingly. Alternatively, to avoid confusion, AP, DV and ML terms are used strictly in relation to the main body, and the terms proximal and distal are used for body segments such as the head, neck and tail (see below).

Proximal and distal

The term proximal (Latin proximus; nearest) is used to describe where the appendage joins the body, and the term distal (Latin distare; to stand away from) is used for the point furthest from the point of attachment to the body. Since appendages often move independently of (and therefore change position with respect to) the main body, these separate directional terms are used when describing them. Latin was the language originally spoken in the region around Rome called Latium. ... A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ...

As noted above, the standard AP, DV and ML directional axes, can cause some confusion when describing parts of the body that can change position (move) relative to the main body. This is particularly true when considering appendages. "Appendages" would include vertebrate fins (see Fig. 2) and limbs (see Figs. 3 and 4), but properly apply to any structure that extends (and can at least potentially move separately) from the main body. Thus, "appendage" would also include such structures as external ears (pinneae) and hair (in mammals), feathers (in birds) and scales (fish, reptiles and birds). As well, varieties of tentacles or and other projections from the body in invertebrates and the male penis in many vertebrates and some invertebrates, would be included. A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ... This article does not cite any references or sources. ... FINS is a network protocol used by Omron PLCs, over different physical networks like Ethernet, Controller Link, DeviceNet and RS-232C. Categories: | ... A limb (from the Old English lim) is a jointed, or prehensile (as octopus tentacles or new world monkey tails), appendage of the human or animal body; a large or main branch of a tree; a representative, branch or member of a group or organization. ... For an alternative meaning, see ear (botany). ... The pinna (Latin for feather) is the visible part of the ear that resides outside of the head (this may also be referred to as the auricle or auricula). ... For the 1968 stage production, see Hair (musical), for the 1979 film, see Hair (film). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Closeup on a single white feather A feather is one of the epidermal growths that forms the distinctive outer covering, or plumage, on a bird. ... For other meanings of bird, see bird (disambiguation). ... In this SEM image of a butterfly wing the scales are clearly visible, and the tiny platelets on each individual scale are just barely visible in the striping. ... For other uses, see Fish (disambiguation). ... Orders  Crocodilia - Crocodilians scary crocodiles. ... Tentacles can refer to the elongated flexible organs that are present in many invertebrates, and sometimes to the hairs of the leaves of insectivorous plants. ... Invertebrate is a term coined by Chevalier de Lamarck to describe any animal without a backbone or vertebra, like insects, squids and worms. ... The penis (plural penises, penes) is an external male sexual organ. ...

By connecting the two points, the proximodistal (sometimes hyphenated to proximo-distal) axis. (The abbreviation AB axis is occasionally, but not commonly, used.) As before, the terms "proximal" and "distal" can be used as relative terms to indicate where structures lie along the proximodistal axis. Thus, the "elbow" is proximal to the hoof, but distal to the "shoulder" in Figs. 3 and 4.

Choosing terms for the other two axes perpendicular to the proximodistal axis could be variable, as they would also depend on the position of the limb. For that reason, when considering any organism, the other two axes are considered to be relative to the appendage when in standard anatomical position. This is roughly defined for all organisms, as in the normal position when at rest and not moving. For tetrapod vertebrates, this includes the caveat that they are standing erect and not lying down. Thus, the fish in Fig. 2, and the horse in Figs. 3 and 4 are in standard anatomical position. (Special considerations with respect to limb position are applied in human anatomy — see below). Groups See text. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ...

Other directional terms

In addition to the three primary axes (AP, DV and the ML half-axis) and the proximodistal axis of appendages, several directional terms can be used in bilaterally symmetrical animals. These terms are strictly relative, and as such do not and cannot be used to define fixed axes. These terms include: In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ...

• Ipsilateral (Latin ipse; self/same): on the same side as another structure. Thus, the left arm is ipsilateral to the left leg.

• Contralateral (Latin contra; against): on the opposite from another structure. Thus, the left arm is contralateral to the right arm, or the right leg.

• Superficial (Latin superfacies; at the surface or face): near the outer surface of the organism. Thus, skin is superficial to the muscle layer. The opposite is "deep", or "visceral".

• Deep: further away from the surface of the organism. Thus, the muscular layer is deep to the skin, but superficial to the intestines. This is one of the few terms where the English vernacular is prevalent. The proper anglicised Latin term would be profound (Latin profundus; due to depth), but this word has other meanings in English. In other languages, the equivalent term is usually similar to "profound" (e.g. profond, meaning deep, in French).

• Intermediate (Latin intermedius; inter, between and medius, middle): between two other structures. Thus, the navel is intermediate to (or intermediate between) the left arm and the contralateral (right) leg.

• Visceral (Latin viscus; internal organs, flesh): organs within the body's cavities. The stomach is within the abdominal cavity, and is thus visceral.

Latin was the language originally spoken in the region around Rome called Latium. ... A term often used in usability enginering or user interface design Often conected with the Emotional feelings in a product signifies the WOW feeling when seeing a new product. ... This article does not cite any references or sources. ...

Invertebrate directional terms

The large variety of body shapes present in invertebrates presents a difficult problem when attempting to apply standard directional terms. Depending on the organism, some terms are taken by analogy from the vertebrate terms, and appropriate novel terms are applied, as necessary. In all cases, the usage of terms is dependent on the bauplan of the organism. It has been suggested that this article or section be merged into body plan. ... It has been suggested that this article or section be merged into body plan. ...

Figure 5: Asymmetrical and spherical body shapes. (a) An organism with an asymmetrical bauplan (Amoeba proteus — an amoeba). (b) An organism with a spherical bauplan (Actinophrys sol — a heliozoan.

Image File history File links Size of this preview: 800 × 379 pixelsFull resolution (1800 × 853 pixel, file size: 474 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Image File history File links Size of this preview: 800 × 379 pixelsFull resolution (1800 × 853 pixel, file size: 474 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... It has been suggested that this article or section be merged into body plan. ... Heliozoa, or sun animalcules, are roughly spherical amoeboids with many stiff, microtubule-supported projections called axopods radiating outward from the cell surface. ...

Asymmetrical and spherical organisms

In organisms with a changeable shape, such as amoeboid organisms (Fig. 5a), directional terms are meaningless, since the shape of the organism is changeable, and no fixed axes are present. Similarly, in organisms that are spherical in shape (Fig. 5b), there is nothing to distinguish one line through the centre of the organism from another. An infinite number of triads of mutually perpendicular axes could be defined, but any such choice of axes would be functionally and practically indistinguishable from all others, and therefore would be useless. In such organisms, only the terms superficial and deep hold any descriptive meaning. Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... For other uses, see sphere (disambiguation). ... Amoeba (Chaos diffluens) Foraminiferan (Ammonia tepida) Heliozoan (Actinophrys sol) Amoeboids are cells that move or feed by means of temporary projections, called pseudopods (false feet). ... In mechanics and geometry, the rotation group is the set of all rotations of 3-dimensional Euclidean space, R3. ...

Figure 6: Four individuals of Phaeodactylum tricornutum, a diatom with a fixed elongated shape.

Image File history File links Size of this preview: 686 × 600 pixelsFull resolution (2403 × 2100 pixel, file size: 1. ... Image File history File links Size of this preview: 686 × 600 pixelsFull resolution (2403 × 2100 pixel, file size: 1. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ...

Elongated organisms

In organisms that maintain a constant shape and have one dimension longer than the other, at least two directional terms can be used. The long or longitudinal axis is defined by points at the opposite ends of the organism. Similarly, a perpendicular transverse axis can be defined by points on opposite sides of the organism. There is typically no basis for the definition of a third axis. Usually such organisms, like that pictured in Fig. 6, are planktonic (free-swimming) protists, and are nearly always viewed on microscope slides, where they appear essentially two-dimensional. In some cases a third axis can be defined, particularly where a non-terminal cytostome or other unique structure is present.^[22] Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... A cytostome or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. ...

Elongated organisms with distinctive ends

Figure 6: Organisms where the ends of the long axis are distinct. (Paramecium caudatum, above, and Stentor roeseli, below.)

Some elongated protists have distinctive ends of the body. In such organisms, the end with a mouth (or equivalent structure, such as the cytostome in Paramecium or Stentor), or the end that usually points in the direction of the organism's locomotion (such as the end opposite the flagellum in Euglena), is normally designated as the anterior end. The opposite end then becomes the posterior end, and by connecting them, an anteroposterior axis is formed.^[23] Properly, this terminology would only apply to an organism that is always planktonic (not normally attached to a surface — as in Fig. 6 top), although the term can also be applied to one that is sessile (normally attached to a surface — as in Fig. 6, bottom and Fig. 7).^[24] Image File history File links Size of this preview: 309 × 599 pixelsFull resolution (1547 × 3000 pixel, file size: 1. ... Image File history File links Size of this preview: 309 × 599 pixelsFull resolution (1547 × 3000 pixel, file size: 1. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... A cytostome or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. ... Species Paramecium tetraurelia Paramecium aurelia Paramecium caudatum The Paramecium is a group of unicellular ciliate protozoa formerly known as slipper animalcules from their slipper shape. ... In Greek mythology, Stentor (Στεντωρ) was a herald of the Greek forces during the Trojan War. ... In biology and physics, animal locomotion is the study of how animals move, and is part of biophysics. ... For the insect anatomical structure, see Antenna (biology). ... Hey Euglena is a common Euglenophyte protist, typical of the euglenids, and commonly found in nutrient-rich freshwater, with a few marine species. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Look up sessile in Wiktionary, the free dictionary. ...

Figure 7: A cluster of Euplectella aspergillum sponges (Venus flower baskets), showing the apical-basal axes.

Organisms that are attached to a substrate, such as sponges (Fig. 7), or some animal-like protists also have distinctive ends. The part of the organism attached to the substrate is usually referred to as the basal end (Latin basis; support or foundation), whereas the end furthest from the attachment is referred to as the apical end (Latin apex; peak, tip). Thus, by joining the two ends, an apical-basal (or basal-apical) axis is formed (see Fig. 7). Transverse axes may be defined indifferently in any direction perpendicular to this axis, as there is no symmetry present. Image File history File links Size of this preview: 753 × 599 pixelsFull resolution (1671 × 1330 pixel, file size: 786 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Image File history File links Size of this preview: 753 × 599 pixelsFull resolution (1671 × 1330 pixel, file size: 786 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Binomial name Euplectella aspergillum Owen, 1841 The Venus Flower Basket, or Euplectella aspergillum, is the only Poriferan in the class Hexactenellida to be used in hobbyists aquariums. ... For other uses, see Substrate. ... The sponge, in the phylum Porifera, is a very primitive and specialized animal. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Pyrrhophyta (dinoflagellates) Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies The Kingdom Protista or Protoctista is one of the commonly recognized biological kingdoms, including all the eukaryotes except for... Latin was the language originally spoken in the region around Rome called Latium. ...

Radially-symmetrical organisms

Radially symmetrical organisms include those in the group Radiata — primarily jellyfish, sea anemones and corals and the comb jellies.^[25][26] Adult echinoderms (sea stars (starfish), sea urchins, and sea cucumbers and others) are also included, since they are pentaradial (i.e. they have fivefold discrete rotational symmetry). Echinoderm larvae are not included, since they are bilaterally symmetrical.^[27][28] In biology, radial symmetry is a property of some multicellular organisms. ... Phyla Cnidaria Ctenophora The Radiata are the radially symmetric animals of the Eumetazoa subregnum. ... Subphylum/Classes[1] Anthozoa — corals and sea anemones Medusozoa:[2] Cubozoa — sea wasps or box jellyfish Hydrozoa — hydroids, hydra-like animals Polypodiozoa Scyphozoa — jellyfish Staurozoa — stalked jellyfish unranked: Myxozoa - parasites Cnidaria[3] (IPA: [4]) is a phylum containing some 11,000 species of apparently simple animals found exclusively in aquatic... Classes Tentaculata Nuda Ctenophores are jellyfish-like animals commonly called comb jellies, sea gooseberries, sea walnuts, or Venus girdles. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... The triskelion appearing on the Isle of Man flag. ... The elaborate patterns on the wings of butterflies are one example of biological symmetry. ... Larvae are the plural of larva, juvenile form of animals with indirect development. ... In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ...

Figure 8: Chrysoara spp. (a jellyfish), showing the oral-aboral, and proximodistal axes. (Note that the appendages are not in standard anatomical position, so that the axis is curved.)

Unlike spherical and asymmetrical organisms, radially-symmetrical animals always have one distinctive axis. Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (2400 × 1800 pixel, file size: 203 KB, MIME type: image/jpeg) Esseh 04:55, 4 April 2007 (UTC) File links The following pages on the English Wikipedia link to this file (pages on other projects are not... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (2400 × 1800 pixel, file size: 203 KB, MIME type: image/jpeg) Esseh 04:55, 4 April 2007 (UTC) File links The following pages on the English Wikipedia link to this file (pages on other projects are not... Bold text For other uses, see Jellyfish (disambiguation). ... A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ...

Figure 9: Aurelia aurita, another species of jellyfish, showing multiple radial and medio-peripheral axes.

Cnidarians have an incomplete digestive system, meaning that one end of the organism has a mouth, and the opposite end has no opening from the gut (coelenteron).^[29] For this reason, the end of the organism with the mouth is referred to as the oral end (Latin oris; mouth), and the opposite surface is the aboral end (Latin ab-; prefix meaning "away from"). Thus, by joining the polar opposite oral and aboral ends, an oral-aboral axis is formed (Fig. 8). Image File history File links Size of this preview: 800 × 341 pixels Full resolution (5269 × 2247 pixel, file size: 7. ... Image File history File links Size of this preview: 800 × 341 pixels Full resolution (5269 × 2247 pixel, file size: 7. ... Bold text For other uses, see Jellyfish (disambiguation). ... Subphylum/Classes[1] Anthozoa — corals and sea anemones Medusozoa:[2] Cubozoa — sea wasps or box jellyfish Hydrozoa — hydroids, hydra-like animals Polypodiozoa Scyphozoa — jellyfish Staurozoa — stalked jellyfish unranked: Myxozoa - parasites Cnidaria[3] (IPA: [4]) is a phylum containing some 11,000 species of apparently simple animals found exclusively in aquatic... Latin was the language originally spoken in the region around Rome called Latium. ...

As with vertebrates, appendages that move independently of the body (tentacles in cnidarians and comb jellies), have a definite proximodistal axis (Fig. 8). Unlike vertebrates, cnidarians (jellyfish, sea anemones, corals) have no other distinctive axes, and multiple radial axes are possible (Fig. 9). A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ... Tentacles can refer to the elongated flexible organs that are present in many invertebrates, and sometimes to the hairs of the leaves of insectivorous plants. ... Subphylum/Classes[1] Anthozoa — corals and sea anemones Medusozoa:[2] Cubozoa — sea wasps or box jellyfish Hydrozoa — hydroids, hydra-like animals Polypodiozoa Scyphozoa — jellyfish Staurozoa — stalked jellyfish unranked: Myxozoa - parasites Cnidaria[3] (IPA: [4]) is a phylum containing some 11,000 species of apparently simple animals found exclusively in aquatic... Classes Tentaculata Nuda Ctenophores are jellyfish-like animals commonly called comb jellies, sea gooseberries, sea walnuts, or Venus girdles. ...

It is noteworthy that some "biradially-symmetrical" comb jellies have distinct "tentacular" and "pharyngeal" axes,^[30] and are thus anatomically equivalent to bilaterally-symmetrical animals. As well, adult echinoderms (starfish, sea urchins, sea cucumbers) are pentaradial, and have only five symmetrical radial axes (unlike the multiple axes in cnidarians). Classes Tentaculata Nuda Ctenophores are jellyfish-like animals commonly called comb jellies, sea gooseberries, sea walnuts, or Venus girdles. ... Illustration of the different types of symmetry of Life Forms On Earth. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ...

"Lateral", dorsal, and ventral have no meaning in such organisms, and all can be replaced by the generic term peripheral (Latin peri-; around; see Table 2). Medial can be used, but in the case of radiates indicates the central point of these organisms, rather than a central axis (as in vertebrates). Thus, as there are many possible radial axes, there are multiple medio-peripheral (half-) axes (Fig. 9).

In biology, radial symmetry is a property of some multicellular organisms. ... In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ... Bilateralism is a term referring to trade or political relations between two states. ... It has been suggested that this article or section be merged into body plan. ... Radiates are multi-cellular organisms characterized by having a body construction involving radial symmetry, and lacking of a central nervous system. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... For other uses, see Substrate. ... In biology, radial symmetry is a property of some multicellular organisms. ...

Medical (human) directional terms

As we are bilaterally-symmetrical organisms, anatomical directions in humans can correctly be described using the same terms as those for vertebrates and other members of the taxonomic group Bilateria. However, for historical and other reasons, standard human directional terminology has several differences from that used for other bilaterally-symmetrical organisms. In biology, bilateral symmetry is a characteristic of multicellular organisms, particularly animals. ... Homo sapiens (Latin: wise man) is the scientific name for the human species. ... Illustration of the different types of symmetry of Life Forms On Earth. ...

Why zootomy and human anatomy terms differ

Although it can be argued that the standard directional nomenclature used for vertebrate zootomy can and should be used for medical anatomy, the differences persist. The differences in terminology arose (and are perpetuated) for three primary reasons: For the chemical substances known as medicines, see medication. ...

• Early human anatomical studies (being within the realm of medicine) were historically conducted separately from, and without reference to, those being done by zootomists.
• Early zoological and human anatomical studies occurred before modern understanding of the process of biological evolution, and humans were widely viewed as "different" from (and "superior to") all other animals, and thus meriting their own terminology.
• Unlike most tetrapod vertebrates, humans are not quadrupedal (walking on four legs), but rather are secondarily bipedal (walking on two legs). Human bipedalism causes shifts in the angle of the appendages (arms and legs) and head, with respect to the main body. Thus, it can be (and is) argued that separate terminology is necessary to adequately describe the unique bipedal stance of humans.

Unfortunately, the persistence of medical terminology as distinct from that used for other vertebrates tends to be confusing. For a quick comparison of equivalent terminology used in vertebrate and human anatomy, see Table 3 (below). List of bones of the human skeleton Human anatomy is primarily the scientific study of the morphology of the adult human body. ... For the chemical substances known as medicines, see medication. ... Zootomy is a contraction of zoological and anatomy and refers to the dissection of animals as opposed to that of plants (phytotomy) See also: Androtomy, zootomical terms for location, Cat anatomy La Anatomía comparada estudia diversas especies. ... This article is about evolution in biology. ... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... The Zebra is an example of a quadruped. ... Bipedalism is standing, or moving for example by walking, running, or hopping, on two appendages (typically legs though it can also include hand walking). ...

This article does not cite any references or sources. ... Zoology (from Greek: ζῴον, zoion, animal; and λόγος, logos, knowledge) is the biological discipline which involves the study of animals. ... Human heart and lungs, from an older edition of Grays Anatomy. ... This article does not cite any references or sources. ... Zootomy is a contraction of zoological and anatomy and refers to the dissection of animals as opposed to that of plants (phytotomy) See also: Androtomy, zootomical terms for location, Cat anatomy La Anatomía comparada estudia diversas especies. ... Human heart and lungs, from an older edition of Grays Anatomy. ... Look up appendage in Wiktionary, the free dictionary. ...

Superior and inferior

As with other vertebrates, two of the most obvious extremes are the "top" and the "bottom" of the organism. In standard anatomical position, these correspond to the head and feet, respectively in humans. The head end is referred to as the superior end (Latin superior: "above"), while the feet are referred to as the inferior end (Latin inferior: "below"). Thus, the axis formed by joining the two is the superior-inferior axis.^[31][32] Latin was the language originally spoken in the region around Rome called Latium. ...

As in other vertebrates, there are synonymous terms for superior and inferior (Table 3). The terms cranial, cephalic, and rostral are occasionally encountered. "Cranial", as a reference to the skull, is fairly commonly used, whereas "cephalic" is uncommonly used, and "rostral" is rarely used in human anatomy.^[33] Similarly, the term caudal is occasionally used in human anatomy,^[34] and the cranio-caudal axis is occasionally encountered. Generally, this usage would only be used with respect to the head and main body (trunk), and not when considering the limbs.

As with vertebrate directional terms, superior and inferior can be used in a relative sense. For example, the shoulders are superior to the navel, but inferior to the eyes. This article is about the body part. ... This article does not cite any references or sources. ... This article refers to the sight organ. ...

Anterior and posterior

Anterior and posterior, as used in medical/human anatomical descriptions are major sources of confusion to those accustomed to standard vertebrate directional terminology, and vice versa. The confusion arises from the differences in standard anatomical positions of quadruped vertebrates and bipedal humans. The Zebra is an example of a quadruped. ... A biped is an animal that travels across surfaces supported by two legs. ...

In human anatomical usage, anterior refers to the "front" of the individual, and is synonymous with ventral. Similarly, posterior, in medical anatomy refers to the "back" of the subject, and is synonymous with dorsal (see Table 3).^[35] The terms "dorsal" and "ventral" are used in human anatomy, but infrequently when referring to the body as a whole.^[36] Thus, the anteroposterior axis is preferred usage for describing the axis connecting the front and the back in humans.^[37][38]

As in other vertebrates, "anterior" and "posterior" can also be used as relative terms. Thus, the eyes are posterior to the nose, but anterior to the back of the head. This article refers to the sight organ. ... For other uses, see Nose (disambiguation). ...

Left and right (lateral), and medial

Left and right lateral are used in the same sense as they are in other vertebrates, as is medial. The left-right axis is rarely used in medicine, however; the mediolateral axis is used almost exclusively.^[39][40]

Appendages

As in other vertebrates, the terms "proximal" and "distal" are used to describe the point of attachment to, and part of an appendage furthest away from, the body, respectively. However, other terms are used for direction in the appendages, given the unique position of the limbs (in standard anatomical position) in humans. A limb (from the Old English lim) is a jointed appendage of the human or animal branch of a tree; a representative, branch or member of a group or organization. ...

Arms

Figure 11: The directional terms used in a human hand.

In standard anatomical position, the palms of the hands point anteriorly. Thus, anterior can be (and sometimes is) used to describe the palm of the hand, and posterior can be (and sometimes is) used to describe the back of the hand and arm. Image File history File links Size of this preview: 800 × 543 pixelsFull resolution (901 × 612 pixel, file size: 225 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... Image File history File links Size of this preview: 800 × 543 pixelsFull resolution (901 × 612 pixel, file size: 225 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Anatomical terms of location ... For other uses, see Hand (disambiguation). ...

However, presumably for improved clarity, the directional term palmar (Latin palma; palm of the hand) is usually used for the anterior of the hand, and dorsal is used to describe the back of the hand. Thus, by connecting the extremes, dorsopalmar axis is formed. Most commonly, "dorsopalmar" is used when describing the hand, although it is sometimes applied to the arm as a whole (see Fig. 11). Latin was the language originally spoken in the region around Rome called Latium. ...

For the third axis, the mediolateral axis suffices, although if referring to the limb alone, "medial" may refer to the centre of the arm itself.

Relative directions

Also, in common usage, the segments of the digestive system closest to the mouth are termed proximal, as opposed to those closest to the anus, which are termed distal. what was here was sick and improperly spelled. ... For other uses, see Mouth (disambiguation). ... This article is about the bodily orifice. ...

Relative directions in the limbs

Specialized terms are used to describe location on appendages, parts that have a point of attachment to the main trunk of the body. Structures that are close to the point of attachment of the body are proximal or central, while ones more distant from the attachment point are distal or peripheral. For example, the hands are at the distal end of the arms, while the shoulders are at the proximal ends. These terms can also be used relatively to organs, for example the proximal end of the urethra is attached to the bladder. In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. ... This article is about the urinary bladder. ...

In the limbs of most animals, the terms cranial and caudal are used in the regions proximal to the carpus (the wrist, in the forelimb) and the tarsus (the ankle in the hindlimb). Objects and surfaces closer to or facing towards the head are cranial; those facing away or further from the head are caudal. In human anatomy, the wrist is the flexible and narrower connection between the forearm and the palm. ... For a review of anatomical terms, see Anatomical position and Anatomical terms of location. ...

Nearer the carpal joint, the term dorsal replaces cranial and palmar replaces caudal. Similarly, nearer the tarsal joint the term dorsal replaces cranial and plantar replaces caudal. For example, the top of a dog's paw is its dorsal surface; the underside, either the palmar (on the forelimb) or the plantar (on the hindlimb) surface. Trinomial name Canis lupus familiaris The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. ... A dogs paw resting on a hard concrete surface. ...

The sides of the forearm are named after its bones: Structures closer to the radius are radial, structures closer to the ulna are ulnar, and structures relating to both bones are referred to as radioulnar. Similarly, in the lower leg, structures near the tibia (shinbone) are tibial and structures near the fibula are fibular (or peroneal). The radius is the bone of the forearm that extends from the outside of your limb to your phlangx (lateral) of the elbow to the thumb side of the wrist. ... The ulna (Elbow Bone) [Figs. ... This article is about the vertebrate bone. ... For other uses see fibula (disambiguation) The fibula or calf bone is a bone placed on the lateral side of the tibia, with which it is connected above and below. ...

Volar (sometimes used as a synonym for "palmar") refers to the underside, for both the palm and the sole (plantar), as in volar pads on the underside of hands, fingers, feet and toes.

The terms valgus and varus are used to refer to angulation of the distal part of a limb at a joint. For example, at the elbow joint, in the anatomical position, the forearm and the upper arm do not lie in a straight line, but the forearm is angulated laterally with respect to the upper arm by about 5–10°. The forearm is said to be "in valgus". Angulation at a joint may be normal (as in the elbow) or abnormal. In orthopedics, a valgus deformity is a term for the outward angulation of the distal segment of a bone or joint. ... In orthopedics, a varus deformity is a term for the inward angulation of the distal segment of a bone or joint. ... This article is about the joint in the arm. ...

Planes

Anatomical planes in a human

Image File history File links BodyPlanes. ... Image File history File links BodyPlanes. ...

General usage

Three basic reference planes are used in zoological anatomy.

• A sagittal plane divides the body into sinister and dexter (left and right) portions.
  • The midsagittal or median plane is in the midline — i.e. it would pass through midline structures such as the navel or spine, and all other sagittal planes (also referred to as parasagittal planes) are parallel to it.
• A coronal or frontal plane divides the body into dorsal and ventral (back and front, or posterior and anterior) portions.
• A transverse plane, also known as an axial plane or cross-section, divides the body into cranial and caudal (head and tail) portions.

For post-embryo 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. The sagittal plane of the human body is an imaginary plane that travels from the top to the bottom of the body, down the midline. ... This article does not cite any references or sources. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ... This page is a candidate for speedy deletion. ... For other uses, see Embryo (disambiguation). ... The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ...

When describing anatomical motion, these planes describe the axis along which an action is performed. So by moving through the transverse plane, movement travels from head to toe. For example, if a person jumped directly up and then down, their body would be moving in the transverse plane.

Some of these terms come from Latin. Sagittal means "like an arrow", a reference to the position of the spine which naturally divides the body into right and left equal halves, the exact meaning of the term "midsagittal".

A longitudinal plane is any plane perpendicular to the transverse plane. The coronal plane and the sagittal plane are examples of longitudinal planes. The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ... The sagittal plane of the human body is an imaginary plane that travels from the top to the bottom of the body, down the midline. ...

Usage in human anatomy

Sometimes the orientation of certain planes needs to be distinguished, for instance in medical imaging techniques such as sonography, CT scans, MRI scans or PET scans. One imagines a human in the anatomical position, and an X-Y-Z coordinate system with the X-axis going from front to back, the Y-axis going from left to right, and the Z-axis going from up to down. The X-axis axis is always forward (Tait-Bryan angles) and the right-hand rule applies. Medical imaging designates the ensemble of techniques and processes used to create images of the human body (or parts thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). ... Sonography redirects here. ... CT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... MRI redirects here. ... Image of a typical positron emission tomography (PET) facility Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three-dimensional image or map of functional processes in the body. ... Fig. ... In geometry, Tait-Bryan angles are three angles used to describe a general rotation in three-dimensional Euclidean space by three successive rotations, once about the x-axis, once about the y-axis, and once about the z-axis. ... The left-handed orientation is shown on the left, and the right-handed on the right. ...

• A transverse (also known as axial or horizontal) plane is an X-Y plane, parallel to the ground, which (in humans) separates the superior from the inferior, or put another way, the head from the feet.

• A coronal (also known as frontal) plane is an Y-Z plane, perpendicular to the ground, which (in humans) separates the anterior from the posterior, the front from the back, the ventral from the dorsal.

• A sagittal (also known as median) plane is an X-Z plane, perpendicular to the ground, which separates left from right. The midsagittal plane is the specific sagittal plane that is exactly in the middle of the body.

The axes and the sagittal plane are the same for bipeds and quadrupeds, but the orientation of the coronal and transverse planes switch. The axes on particular pieces of equipment may or may not correspond to axes of the body, especially since the body and the equipment may be in different relative orientations. In sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons. ... In sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons. ... Fig. ... The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ...

Occasionally, in medicine, abdominal organs may be described with reference to the trans-pyloric plane which is a transverse plane passing through the pylorus. For the human abdomen, see human abdomen. ... From Greek pylorus; pyl- = gate, -orus = guard. ...

Anatomical planes in animal brains

In discussing the neuroanatomy of animals, particularly rodents used in neuroscience research, the convention has been to name the sections of the brain according to the homologous human sections. Hence, what is technically a transverse section with respect to the body of a rat (dividing anterior from posterior) may often be referred to in rat neuroanatomical coordinates as a coronal section, and likewise a coronal section with respect to the body (ie. dividing ventral from dorsal) in a rat brain is referred to as transverse. This preserves the comparison with the human brain which is rotated with respect to the body axis by 90 degrees in the ventral direction. It does mean that the planes of the rat brain are not necessarily the same as those of the body. Neuroanatomy is the anatomy of the nervous system. ... Suborders Sciuromorpha Castorimorpha Myomorpha Anomaluromorpha Hystricomorpha Rodentia is an order of mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must be kept short by gnawing. ... Drawing of the cells in the chicken cerebellum by S. Ramón y Cajal Neuroscience is a field that is devoted to the scientific study of the nervous system. ...

Surface and other landmarks in humans

In humans, reference may be made to landmarks which are on the skin or visible underneath. As with planes, lines and points are imaginary. Examples include:

• The mid-axillary line, a line running vertically down the surface of the body passing through the apex of the axilla (armpit). Parallel are the anterior axillary line, which passes through the anterior axillary skinfold, and the posterior axillary line, which passes through the posterior axillary skinfold.
• The mid-clavicular line, a line running vertically down the surface of the body passing through the midpoint of the clavicle.
• The mid-pupillary line, a line running vertically down the face through the midpoint of the pupil when looking directly forwards.
• The mid-inguinal point, a point midway between the anterior superior iliac spine and the pubic symphysis.
  • mid-point of inguinal ligament = mid-point between anterior superior iliac spine and pubic tubercle
• Tuffier's line, which is a transverse line passing across the lumbar spine between the posterior iliac crests.
• Mid-ventral line, the intersection between the ventral skin and the median plane.

Additionally, reference may be made to structures at specific levels of the spine (e.g. the 4th cervical vertebra, abbreviated "C4"), or the rib cage (e.g. the 5th intercostal space, abbreviated "5ICS"). The armpit (or axilla) is the area on the human body directly under the area where the arm connects to the shoulder. ... The midclavicular line (or midclavicular plane) is a vertical line crossing through the clavicle. ... Collarbone and collar bone redirect here. ... The human eye The pupil is the central transparent area (showing as black). ... The term Illion, Ilium has several meanings, including in legends, in anatomy, and in the arts: Ilion or Ilium is an alternative name for the legendary city of Troy. ... The pubic symphysis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones (pubis). ... The ilium of the pelvis is divisible into two parts, the body and the ala; the separation is indicated on the internal surface by a curved line, the arcuate line, and on the external surface by the margin of the acetabulum. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... A diagram of a thoracic vertebra. ... Intercostal spaces, viewed from the left The intercostal space is the space between two ribs (Lat. ...

Relative motions

Main article: Anatomical terms of motion

It has been suggested that Kinesiology#Motions be merged into this article or section. ...

Notes

References

• Atkins, B.T., Duval, A., Lewis, H.M.A., and Milne, R.C. (1993) Collins-Robert French-English, English-French Dictionary, 2^nd ed. HarperCollins, Glasgow UK and Le Robert, Paris, France. ISBN 0-06-275513-7.

• Barber, K., ed. (1998) The Canadian Oxford English Dictionary. Oxford University Press, Don Mills, ON, Canada. ISBN 0-19-541120-X.

• Campbell, N.A. and Reece, J.B. (2005) Biology, 7^th ed. Pearson, San Francisco, CA, USA. ISBN 0-8053-7166-4.

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• Marieb, E.N. (1995) Human Anatomy and Physiology, 3^rd ed. Benjamin/Cummings, Redwood City, CA, USA. ISBN 0-8053-4281-8.

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External links

• Directions, cross sections, and divisions of the human brain
• Anatomy of the lower limb