Anatomical terms of location
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Standard anatomical terms of location are used to unambiguously describe the
The meaning of terms that are used can change depending on whether an organism is
International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example,
Introduction
Standard
Different terms are used for groups of creatures with different body layouts, such as
Standard anatomical position
Because animals can change orientation with respect to their environment, and because appendages like limbs and tentacles can change position with respect to the main body, terms to describe position need to refer to an animal when it is in its standard anatomical position.[1] This means descriptions as if the organism is in its standard anatomical position, even when the organism in question has appendages in another position. This helps avoid confusion in terminology when referring to the same organism in different postures.[1] In humans, this refers to the body in a standing position with arms at the side and palms facing forward, with thumbs out and to the sides.[2][1]
Combined terms
Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body. For example, "anterolateral" indicates a position that is both anterior and lateral to the body axis (such as the bulk of the pectoralis major muscle).
In
Planes
Anatomical terms describe structures with relation to four main anatomical planes:[2]
- The median plane, which divides the body into left and right.[2][6] This passes through the head, spinal cord, navel, and, in many animals, the tail.[6]
- The sagittal planes, which are parallel to the median plane.[1]
- The frontal plane, also called the coronal plane, which divides the body into front and back.[2]
- The horizontal plane, also known as the transverse plane, which is perpendicular to the other two planes.[2] In a human, this plane is parallel to the ground; in a quadruped, this divides the animal into anterior and posterior sections.[3]
Axes
The axes of the body are lines drawn about which an organism is roughly symmetrical.[7] To do this, distinct ends of an organism are chosen, and the axis is named according to those directions. An organism that is symmetrical on both sides has three main axes that intersect at right angles.[3] An organism that is round or not symmetrical may have different axes.[3] Example axes are:
Examples of axes in specific animals are shown below.
-
Anatomical axes in a human, similar for other orthograde bipedal vertebrates
-
Anatomical axes and directions in a fish
-
testes may be measured by long and short axes.[11]
Modifiers
Several terms are commonly seen and used as prefixes:
- Sub- (from Latin sub 'preposition beneath, close to, nearly etc') is used to indicate something that is beneath, or something that is subordinate to or lesser than.[12] For example, subcutaneousmeans beneath the skin.
- Hypo- (from Ancient Greek ὑπό 'under') is used to indicate something that is beneath.[13] For example, the hypoglossal nervesupplies the muscles beneath the tongue.
- Infra- (from Latin infra 'under') is used to indicate something that is within or below.[14] For example, the infraorbital nerve runs within the orbit.
- Inter- (from intercostal muscles run between the ribs.
- Super- or Supra- (from supraorbital ridges are above the eyes.
Other terms are used as suffixes, added to the end of words:
- -ad (from Latin ab) are used to indicate that something is towards (-ad) or away from (-ab) something else.[17][18] For example, "distad" means "in the distal direction", and "distad of the femur" means "beyond the femur in the distal direction". Further examples may include cephalad (towards the cephalic end), craniad, and proximad.[19]
Main terms
Superior and inferior
Superior (from
Anterior and posterior
Anterior (from
Medial and lateral
These terms describe how close something is to the midline, or the medial plane. are medial to the legs. Temporal has a similar meaning to lateral but is restricted to the head.
The terms "left" and "right" are sometimes used, or their Latin alternatives (
Terms derived from lateral include:
- Contralateral (from Latin contra 'against'): on the side opposite to another structure.[24] For example, the right arm and leg are controlled by the left, contralateral, side of the brain.
- Ipsilateral (from Latin ipse 'same'): on the same side as another structure.[25]For example, the left arm is ipsilateral to the left leg.
- Bilateral (from testeson both sides of the body.
- Unilateral (from , meaning weakness on one side of the body.
Proximal and distal
The terms proximal (from
"Proximal and distal" are frequently used when describing
The terms are also applied to internal anatomy, such as to the reproductive tract of snails. Unfortunately, different authors use the terms in opposite senses. Some consider "distal" as further from a point of origin near the centre of the body and others as further from where the organ reaches the body's surface; or other points of origin may be envisaged.[31]
This terminology is also employed in molecular biology and therefore by extension is also used in chemistry, specifically referring to the atomic loci of molecules from the overall moiety of a given compound.[32]
Central and peripheral
Central and peripheral refer to the distance towards and away from the centre of something.[33] That might be an organ, a region in the body, or an anatomical structure. For example, the central nervous system and the peripheral nervous systems.
Central (from
Peripheral (from
Superficial and deep
These terms refer to the distance of a structure from the surface.[2]
Deep (from
Superficial (from
Dorsal and ventral
These two terms, used in anatomy and embryology, describe something at the back (dorsal) or front/belly (ventral) of an organism.[2]
The dorsal (from
The ventral (from
For example, in a fish, the
Rostral, cranial, and caudal
Specific terms exist to describe how close or far something is to the head or tail of an animal. To describe how close to the head of an animal something is, three distinct terms are used:
- Rostral (from Latin rostrum 'beak, nose') describes something situated toward the oral or nasal region, or in the case of the brain, toward the tip of the frontal lobe.[39]
- Cranial (from Greek κρανίον 'skull') or cephalic (from Greek κεφαλή 'head') describes how close something is to the head of an organism.[40]
- Caudal (from Latin cauda 'tail') describes how close something is to the trailing end of an organism.[41]
For example, in horses, the eyes are caudal to the nose and rostral to the back of the head.
These terms are generally preferred in veterinary medicine and not used as often in human medicine.[42][43][44] In humans, "cranial" and "cephalic" are used to refer to the skull, with "cranial" being used more commonly. The term "rostral" is rarely used in human anatomy, apart from embryology, and refers more to the front of the face than the superior aspect of the organism. Similarly, the term "caudal" is used more in embryology and only occasionally used in human anatomy.[2] This is because the brain is situated at the superior part of the head whereas the nose is situated in the anterior part. Thus, the "rostrocaudal axis" refers to a C shape (see image).
Other terms and special cases
Anatomical landmarks
The location of anatomical structures can also be described in relation to different
Structures may be described as being at the level of a specific
References may also take origin from
Anatomical lines are used to describe anatomical location. For example, the mid-clavicular line is used as part of the cardiac exam in medicine to feel the apex beat of the heart.
Mouth and teeth
Special terms are used to describe the mouth and teeth.
Hands and feet
Several anatomical terms are particular to the hands and feet.[2]
Additional terms may be used to avoid confusion when describing the surfaces of the hand and what is the "anterior" or "posterior" surface. The term "anterior", while anatomically correct, can be confusing when describing the
In humans, volar can also be used synonymously with palmar to refer to the underside of the palm, but plantar is used exclusively to describe the sole. These terms describe location as palmar and plantar; For example, volar pads are those on the underside of hands or fingers; the plantar surface describes the sole of the heel, foot or toes.
Similarly, in the forearm, for clarity, the sides are named after the 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).
Rotational direction
Anteversion and retroversion are complementary terms describing an anatomical structure that is rotated forwards (towards the front of the body) or backwards (towards the back of the body), relative to some other position. They are particularly used to describe the curvature of the uterus.[49][50]
- Anteversion (from may be anteverted, that is to say tilted forward to some relevant degree.
- Retroversion (from Latin retroversus) describes an anatomical structure tilted back away from something.[50] An example is a retroverted uterus.[50]
Other directional terms
Several other terms are also used to describe location. These terms are not used to form the fixed axes. Terms include:
- Axial (from Latinaxis 'axle'): around the central axis of the organism or the extremity. Two related terms, "abaxial" and "adaxial", refer to locations away from and toward the central axis of an organism, respectively
- Luminal (from serosa, or the cavity's wall).[54]
- Parietal (from parietal peritoneum is the lining on the inside of the abdominal cavity. Parietal can also refer specifically to the parietal boneof the skull or associated structures.
- Terminal (from Latin terminus 'boundary or end') at the extremity of a usually projecting structure.[56]For example, "...an antenna with a terminal sensory hair".
- Visceral and viscus (from Latin viscera 'internal organs'): associated with organs within the body's cavities.[57] For example, the stomach is covered with a lining called the visceral peritoneum as opposed to the parietal peritoneum. Viscus can also be used to mean "organ".[57]For example, the stomach is a viscus within the abdominal cavity, and visceral pain refers to pain originating from internal organs.
- Aboral (opposite to oral) is used to denote a location along the
Specific animals and other organisms
Different terms are used because of different body plans in animals, whether animals stand on one or two legs, and whether an animal is symmetrical or not, as discussed above. For example, as humans are approximately bilaterally symmetrical organisms, anatomical descriptions usually use the same terms as those for other vertebrates.[59] However, humans stand upright on two legs, meaning their anterior/posterior and ventral/dorsal directions are the same, and the inferior/superior directions are necessary.[60] Humans do not have a beak, so a term such as "rostral" used to refer to the beak in some animals is instead used to refer to part of the brain;[61] humans do also not have a tail so a term such as "caudal" that refers to the tail end may also be used in humans and animals without tails to refer to the hind part of the body.[62]
In
-
Anatomical terms of location in a dog
-
Anatomical terms of location in a kangaroo
-
Anatomical terms of location in a fish
-
Anatomical terms of location in a horse
Asymmetrical and spherical organisms
In organisms with a changeable shape, such as
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 are
Some elongated
Organisms that are attached to a
Radially symmetrical organisms
Radially symmetrical organisms always have one distinctive axis.Unlike vertebrates, cnidarians have only a single distinctive axis. "Lateral", "dorsal", and "ventral" have no meaning in such organisms, and all can be replaced by the generic term peripheral (from
-
Aurelia aurita, another species of jellyfish, showing multiple radial and medio-peripheral axes
-
Thesea star Porania pulvillus, aboral and oral surfaces
Spiders
Special terms are used for
-
Aspects of spider anatomy. This aspect shows the mainly prolateral surface of the anterior femora, plus the typical horizontal eye pattern of theSparassidae.
-
Typical arrangement of eyes in theLycosidae, with PME being the largest
-
In theSalticidaethe AME are the largest.
See also
- Chirality
- Geometric terms of location
- Handedness
- Laterality
- Proper right and proper left
- Reflection symmetry
- Sinistral and dextral
References
Citations
- ^ a b c d e f g h i Dyce, Sack & Wensing 2010, pp. 2–3.
- ^ a b c d e f g h i j k l m n o Gray's Anatomy 2016, pp. xvi–xvii.
- ^ a b c d Kardong's 2019, p. 16.
- ISBN 978-3-13-144211-6.
- ^ "dorsolateral". Merriam-Webster. 29 September 2023.
- ^ a b Wake 1992, p. 6.
- ^ Collins 2020, "axis", accessed 17 July 2020.
- ^ Merriam-Webster 2020, "Anteroposterior", accessed 14 October 2020.
- ^ Merriam-Webster 2020, "Cephalocaudal", accessed 14 October 2020.
- ^ Merriam-Webster 2020, "Dorsoventral", accessed 14 October 2020.
- ISBN 978-1-4557-3766-6.
- ^ Merriam-Webster 2020, "Sub-", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "Hypo-", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "Infra-", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "Inter-", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "Super-" and "Supra-", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "-ad", accessed on 3 July 2020.
- ^ Merriam-Webster 2020, "an-", accessed on 17 July 2020.
- ISBN 978-1845935429.
- ^ Collins 2020, "superior", accessed 2 July 2020.
- ^ Collins 2020, "inferior", accessed 2 July 2020.
- ^ Collins 2020, "anterior", accessed 2 July 2020.
- ^ Collins 2020, "posterior", accessed 2 July 2020.
- ^ Collins 2020, "contralateral", accessed 2 July 2020.
- ^ Collins 2020, "ipsilateral", accessed 2 July 2020.
- ^ Collins 2020, "bilateral", accessed 2 July 2020.
- ^ Collins 2020, "unilateral", accessed 2 July 2020.
- ^ Collins 2020, "varus" and "valgus", accessed 17 July 2020.
- ^ Wake 1992, p. 5.
- ^ "What do distal and proximal mean?". The Survival Doctor. 2011-10-05. Retrieved 2016-01-07.
- ^ Hutchinson, J.M.C. (2022). "Lippen are not lips, and other nomenclatural confusions". Mitteilungen der Deutschen Malakozoologischen Gesellschaft. 107: 3–7.
- PMID 11749256.
- ^ a b Collins 2020, "central", accessed 17 July 2020.
- ^ Collins 2020, "peripheral", accessed 17 July 2020.
- ^ Collins 2020, "deep", accessed 2 July 2020.
- ^ Collins 2020, "profound", accessed 2 July 2020.
- ^ Collins 2020, "superficial", accessed 2 July 2020.
- ^ a b GO 2014, "dorsal/ventral axis specification" (GO:0009950).
- ^ Merriam-Webster 2020, "rostral", accessed 3 July 2020.
- ^ Merriam-Webster 2020, "cranial" and "cephalic", accessed 3 July 2020.
- ^ Merriam-Webster 2020, "caudal", accessed 3 July 2020.
- ^ ISBN 0-07-234903-4
- ISBN 0-07-243559-3
- ^ ISBN 0-03-025982-7.
- ^ ISBN 978-0-521-48110-6.
- ISBN 978-0-12-746612-5.
- S2CID 8134718.
- ^ ISBN 978-93-86691-16-3.
- ^ a b Collins 2020, "anteversion", accessed 17 July 2020.
- ^ a b c Collins 2020, "retroversion", accessed 17 July 2020.
- ^ William C. Shiel. "Medical Definition of Lumen". MedicieNet. Retrieved 12 December 2020.
- ^ "NCI Dictionary of Cancer Terms "lumen"". National Cancer Institute. Retrieved 12 December 2020.
- ^ ""abluminal"". Merriam-Webster.com Medical Dictionary. Retrieved 12 December 2020.
- ^ David King (2009). "Study Guide - Histology of the Gastrointestinal System". Southern Illinois University. Retrieved 12 December 2020.
- ^ Merriam-Webster 2020, "parietal", accessed 3 July 2020.
- ^ Merriam-Webster 2020, "terminal", accessed 3 July 2020.
- ^ a b Merriam-Webster 2020, "visceral", accessed 3 July 2020.
- PMID 30779310.
- ^ Wake 1992, p. 1.
- ^ Tucker, T. G. (1931). A Concise Etymological Dictionary of Latin. Halle (Saale): Max Niemeyer Verlag.
- ^ Merriam-Webster 2020, "rostral", accessed 14 October 2020.
- ^ Merriam-Webster 2020, "caudal", accessed 14 October 2020.
- ISBN 978-0-226-84548-7.
- ^ Collins 2020, "oral", accessed 13 October 2020.
- ^ Merriam-Webster 2020, "aboral", accessed 13 October 2020.
- ^ Oliveira, Otto Müller Patrão de. "Chave de identificação dos Ctenophora da costa brasileira". Biota Neotropica. Retrieved 6 April 2023.
- ^ Ruppert et al. (2004), p. 184.
- OCLC 668250654.
- ^ ISBN 978-0-19-973482-5.
General sources
- "Collins Online Dictionary | Definitions, Thesaurus and Translations". collinsdictionary.com.
- Dyce, KM; Sack, WO; Wensing, CJG (2010). Textbook of veterinary anatomy (4th ed.). St. Louis, Missouri: Saunders/Elsevier. ISBN 9781416066071.
- "GeneOntology". GeneOntology. The Gene Ontology Consortium. Retrieved 26 October 2014.
- Standring, Susan, ed. (2016). Gray's anatomy: the anatomical basis of clinical practice (41st ed.). Philadelphia: Elsevier Limited. OCLC 920806541.
- Kardong, Kenneth (2019). Vertebrates: comparative anatomy, function, evolution (8th ed.). New York: McGraw-Hill. ISBN 9781260092042.
- "Dictionary by Merriam-Webster: America's most-trusted online dictionary". www.merriam-webster.com.
- Wake, Marvale H., ed. (1992). Hyman's comparative vertebrate anatomy (3rd ed.). Chicago: University of Chicago Press. ISBN 9780226870113.