# Leg

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Leg
> Markdown URL: https://mediated.wiki/source/Leg.md
> Source: https://en.wikipedia.org/wiki/Leg
> Source revision: 1306955096
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{short description|Weight bearing and locomotive anatomical structure}}
{{Redirect|Legs|specifically legs in humans|Human leg||Leg (disambiguation)}}
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{{Infobox anatomy
| Name       = Leg
| Latin      = membrum inferius
| Greek      =
| Image      = InsectLeg.svg
| Caption    = Diagram of an insect leg
| Width      =
| Image2     =
| Caption2   =
| Precursor  =
| System     =
| Artery     =
| Vein       =
| Nerve      =
| Lymph      =
}}
A '''leg''' is a [weight-bearing](/source/weight-bearing) and [locomotive](/source/animal_locomotion) anatomical structure, usually having a [column](/source/column)ar shape. During locomotion, legs function as "extensible struts".<ref>{{cite journal |title=Studies in the Mechanics of the Tetrapod Skeleton |date=1944 |publisher=Biologists.org |doi=10.1242/jeb.20.2.88 |url=http://jeb.biologists.org/cgi/content/abstract/20/2/88 |access-date=21 September 2010 |url-status=live |archive-url=https://web.archive.org/web/20080709010059/http://jeb.biologists.org/cgi/content/abstract/20/2/88 |archive-date=9 July 2008 |last1=Gray |first1=J. |journal=Journal of Experimental Biology |volume=20 |issue=2 |pages=88–116 |bibcode=1944JExpB..20...88G }}</ref>  The combination of movements at all joints can be modeled as a single, linear element capable of changing length and rotating about an omnidirectional "hip" joint.

As an anatomical [animal](/source/animal) structure, it is used for [locomotion](/source/animal_locomotion). The [distal](/source/Anatomical_terms_of_location) end is often modified to distribute [force](/source/force) (such as a [foot](/source/foot)). Most animals have an even number of legs.

As a component of furniture, it is used for the economy of materials needed to provide the support for the useful surface, such as the table top or chair seat.

==Terminology==
*[Uniped](/source/Unipedalism): one leg, such as clams
*[Biped](/source/Bipedalism): two legs, such as humans and birds
*[Triped](/source/Tripedalism): three legs, which typically does not occur naturally in healthy animals
*[Quadruped](/source/Quadrupedalism): four legs, such as dogs and horses

Many [taxa](/source/taxa) are characterized by the number of legs:
*[Tetrapod](/source/Tetrapod)s have four legs. Squamates of genus ''[Bipes](/source/Bipes_(lizard))'' have only two. Caecilians and many squamate lineages convergently lost their legs.
*[Panarthropoda](/source/Panarthropoda): no less than four legs. Velvet worms and some arthropods have more than a dozen legs; a few species possess over one hundred. Despite what their names might suggest, [centipede](/source/centipede)s ("hundred feet") may have fewer than twenty or more than 300 legs, and [millipede](/source/millipede)s ("thousand feet") have fewer than 1,000 legs, but up to 750.

==Components==
A leg is a structure of [gross anatomy](/source/gross_anatomy), meaning that it is large enough to be seen unaided.  The components depend on the animal.  In humans and other mammals, a leg includes the [bone](/source/bone)s, [muscle](/source/muscle)s, [tendon](/source/tendon)s, [ligament](/source/ligament)s, [blood vessel](/source/blood_vessel)s, [nerve](/source/nerve)s, and [skin](/source/skin).  In [insect](/source/insect)s, the leg includes most of these things, except that insects have an [exoskeleton](/source/exoskeleton) that replaces the function of both the bones and the skin.

Sometimes the end of the leg, or [foot](/source/foot), is considered part of the leg; other times it is considered separate.  Similarly, the [hip joint](/source/hip_joint) or other place where the leg attaches to the main body may be considered separate or part of the leg.

==Tetrapod legs==
[[File:Mammoth leg.png|thumb|upright=0.6|The leg of a [woolly mammoth](/source/woolly_mammoth) (reconstruction)]]

In [tetrapod](/source/tetrapod) [anatomy](/source/anatomy), ''leg'' is used to refer to the entire [limb](/source/Limb_(anatomy)). In human medicine, the precise definition refers<ref>{{cite web |title=Leg |work=Medical Subject Headings (MeSH) |publisher=National Library of Medicine |url=https://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=Leg&field=entry |access-date=18 April 2009 |url-status=dead |archive-url=https://web.archive.org/web/20151222151236/http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=Leg&field=entry |archive-date=22 December 2015 }}</ref><ref>{{cite web |title=Leg |work=Dorland's Medical Dictionary for Healthcare Consumers |publisher=Mercksource |url=http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/five/000058188.htm |archive-url=https://archive.today/20111014042937/http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/five/000058188.htm |url-status=dead |archive-date=14 October 2011 |access-date=18 April 2009 }}</ref><ref>{{MerriamWebsterDictionary|leg}}</ref> only to the segment between the [knee](/source/knee) and the [ankle](/source/ankle). This lower segment is also called the ''shank'',<ref>{{cite book |last=Kardong |first=Kenneth V. |date=2009 |title=Vertebrates: Comparative anatomy, function, evolution |edition=5th |publisher=McGraw-Hill |isbn=978-0-07-304058-5 |page=340}}</ref><ref>{{MerriamWebsterDictionary|shank}}</ref> and the front (anterior) of the segment is called the ''shin'' or ''pretibia''.

In [biped](/source/biped)al [tetrapod](/source/tetrapod)s, the two lower limbs are referred to as the "legs" and the two upper limbs as "arms" or "wings" as the case may be.  In quadrupedal tetrapods, the limbs are generally called forelegs, fore legs or front legs and hindlegs, hind legs or back legs.

==Robotic leg==
A [robotic leg](/source/robotic_leg) is moved by an [actuator](/source/actuator), which is a type of [motor](/source/Engine) for moving or controlling a mechanism or system.  It is operated by a source of energy, usually in the form of an electric current, [hydraulic fluid](/source/hydraulic_fluid) pressure or [pneumatic](/source/pneumatic) pressure, and converts that energy into motion.

==Prosthetic leg==
[[File:86 ACPS Atlanta 1996 Swimming General Views.jpg|thumb|right|[Cameron de Burgh](/source/Cameron_de_Burgh), an Australian Paralympic swimmer, who has a prosthetic leg]]
A [prosthetic](/source/prosthesis) leg is an artificial leg that is used to replace one that has been lost.

==References==
{{Reflist|30em}}

==External links==
* {{commons-inline}}

{{Authority control}}
{{Use dmy dates|date=April 2024}}

Category:Animal locomotion
Category:Animal anatomy
Category:Lower limb anatomy

[cs:Noha](/source/cs%3ANoha)

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Adapted from the Wikipedia article [Leg](https://en.wikipedia.org/wiki/Leg) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Leg?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.