Peripheral (from Latin peripheria, originally from Ancient Greek) describes something further away from the centre of something. [65] Usually, the eyes are arranged in two roughly parallel, horizontal and symmetrical rows of eyes. For the linguistic terms, see, Aspects of spider anatomy; This aspect shows the mainly prolateral surface of the anterior femora, plus the typical horizontal eye pattern of the, 'preposition beneath, close to, nearly etc', Better performance or individual preference for use of a hand, Preference most humans show for one side of their body over the other, terms for unambiguous directions, like port and starboard. As with planes, lines and points are imaginary. Because the sacrum and coccyx are fused, they are not often used to provide the location.
The ulna is usually slightly longer than the radius, but the radius is thicker. In some cases a third axis can be defined, particularly where a non-terminal cytostome or other unique structure is present. [1] [36]. 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. [3], 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. It is important to keep this in mind to ensure consistency of description. Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. The name derives from the Classical Latin word for trowel or small shovel, which it was thought to resemble. The problem in consistency of naming occurs when ambiguous terms like "top" are used, which would be considered the head of a human, whereas for a flounder, the "top" would be the left or right side. Because animals can change orientation 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. Thus, the pectoral fins are dorsal to the anal fin, but ventral to the dorsal fin. The terms valgus and varus are used to refer to angulation of the distal part of a limb at a joint. The structures of the human neck are anatomically grouped into four compartments; vertebral, visceral and two vascular compartments. An indefinite number of triads of mutually perpendicular axes could be defined, but any such choice of axes would be useless, as nothing would distinguish a chosen triad from any others. In all cases, the usage of terms is dependent on the body plan of the organism. Anatomical terms of location in a kangaroo. For example, in a fish, the pectoral fins are dorsal to the anal fin, but ventral to the dorsal fin. [14] Similarly, the term caudal is occasionally used in human anatomy,[15] and the cranio-caudal axis is occasionally encountered. [39], The ventral (from Latin venter 'belly') surface refers to the front, or lower side, of an organism.[39]. Although the direction indicated by "proximal" and "distal" is always respectively towards or away from the point of attachment, a given structure can be either proximal or distal in relation to another point of reference. Within these compartments, the neck houses the cervical vertebrae and cervical part of the spinal cord, upper parts of the respiratory and digestive tracts, endocrine glands, nerves, arteries and veins. Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. [43][44][45] In humans, "cranial" and "cephalic" are used to refer to the skull, with "cranial" being used more commonly. In organisms with a changeable shape, such as amoeboid organisms, most directional terms are meaningless, since the shape of the organism is not constant and no distinct axes are fixed. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes. 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. [49] [50]. Specific terms exist to describe how close or far something is to the head or tail of an animal. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands, feet, and eyes. For example, as humans are approximately bilaterally symmetrical organisms, anatomical descriptions usually use the same terms as those for vertebrates.
[2] [1], 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. 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. Varus (from Latin 'bow-legged') and valgus (from Latin 'knock-kneed') are terms used to describe a state in which a part further away is abnormally placed towards (varus) or away from (valgus) the midline.[30]. These terms are used to avoid confusion when describing the median surface of the hand and what is the "anterior" or "posterior" surface – "anterior" can be used to describe the palm of the hand, and "posterior" can be used to describe the back of the hand and arm. Internal features can also show symmetry, for example the tubes in the human body which are cylindrical and have several planes of symmetry. [43][45] Radially symmetrical organisms always have one distinctive axis. They are universal terms that may be readily understood by zoologists who speak any language.. 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. [24]. By connecting the outermost points the dorsoventral axis is formed (sometimes hyphenated: dorso-ventral). Prolateral refers to the surface of a leg that is closest to the anterior end of an arachnid's body. Directions, cross sections, and divisions of the human brain, https://www.wikidoc.org/index.php?title=Anatomical_terms_of_location&oldid=668439, Creative Commons Attribution/Share-Alike License, Early zoological and human anatomical studies occurred before modern understanding of the process of, Unlike most tetrapod vertebrates, humans are not, mid-point of inguinal ligament = mid-point between anterior superior iliac spine and pubic tubercle, Atkins, B.T., Duval, A., Lewis, H.M.A., and Milne, R.C. 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. Hickman, C. P., Jr., Roberts, L. S. and Larson, A.
The last axis, by geometric definition, must be at right angles to both the AP and DV axes. 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. The radius or bot bone is one of the two large bones of the forearm, the other being the ulna. Some of these terms come from Latin. These terms are strictly relative, and as such do not and cannot be used to define fixed axes. In organisms that maintain a constant shape and have one dimension longer than the other, at least two directional terms can be used. Central and peripheral refer to the distance towards and away from the centre of something. sv:Anatomiska termer för läge. 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. de:Lage- und Richtungsbezeichnungen These terms are frequently used when describing appendages such as fins, tentacles, limbs or any structure that extends that can potentially move separately from the main body.
Because animals can change orientation with respect to their environment, and because appendages can change position with respect to the main body, it is important that anatomical terms of location refer to the organism when it is in its standard anatomical position.
"Lateral", "dorsal", and "ventral" have no meaning in such organisms, and all can be replaced by the generic term peripheral (from Ancient Greek περιφέρεια 'circumference'). [2], The dorsal (from Latin dorsum 'back') surface of an organism refers to the back, or upper side, of an organism. For improved clarity, the directional term palmar (from Latin palma 'palm of the hand') is usually used to describe the front of the hand, and dorsal is the back of the hand.