Editing Ligament

{{Short description|Connective tissue between bones}}
{{for|the structure of a bivalve shell|Ligament (bivalve)}}

{{More citations needed|date=October 2010}}

{{Infobox anatomy
| Name        = Ligament
| Latin       = ligamentum ([[Plural]]: ligamenta)
| Image       = 
| Caption     = 
| Width       = 
| Image2      = 
| Caption2    = 
| Function    = Connect bones to other bones; maintain position of organs
| Precursor   = 
| System      = [[Musculoskeletal system]]
| Artery      = 
| Vein        = 
| Nerve       = 
| Lymph       = 
}}
A '''ligament''' is a type of [[Connective tissue#Types|fibrous connective tissue]] in the body that connects [[bone]]s to other bones. It also connects [[Flight_feather#Remiges|flight feathers]] to bones, in dinosaurs and birds. All 30,000 species of [[amniotes]] (land animals with internal bones) have ligaments. 

It is also known as ''articular ligament'', ''articular larua'',<ref>{{DorlandsDict|five/000059130|ligament}}</ref> ''fibrous ligament'', or ''true ligament''.

==Comparative anatomy==
Ligaments are similar to [[tendon]]s and [[fascia]]e as they are all made of [[connective tissue]].<ref>{{Cite journal |last1=Asahara |first1=Hiroshi |last2=Inui |first2=Masafumi |last3=Lotz |first3=Martin K. |date=September 2017 |title=Tendons and Ligaments: Connecting Developmental Biology to Musculoskeletal Disease Pathogenesis |journal=Journal of Bone and Mineral Research |volume=32 |issue=9 |pages=1773–1782 |doi=10.1002/jbmr.3199 |issn=0884-0431 |pmc=5585011 |pmid=28621492}}</ref> The differences among them are in the connections that they make: ligaments connect one bone to another bone, tendons connect muscle to bone, and fasciae connect muscles to other muscles. These are all found in the [[skeletal system]] of the [[human body]]. Ligaments cannot usually be regenerated naturally; however, there are [[periodontal ligament stem cells]] located near the periodontal ligament which are involved in the adult regeneration of periodontist ligament.

The study of ligaments is known as {{wt|en|desmology}}.

==Humans==
Other ligaments in the body include the:
* [[Peritoneal ligament]]: a fold of [[peritoneum]] or other membranes.
* [[Fetal remnant ligament]]: the remnants of a [[fetus|fetal]] tubular structure.
* [[Periodontal ligament]]: a group of fibers that attach the [[cementum]] of [[tooth|teeth]] to the surrounding [[alveolar process|alveolar bone]].
==Articular ligaments ==
[[File:Ligament.jpg|thumb|262x262px|Articular ligament]]
"Ligament" most commonly refers to a band of [[dense regular connective tissue]] bundles made of [[collagen]]ous fibers, with bundles protected by [[dense irregular connective tissue]] sheaths.  Ligaments connect bones to other bones to form [[joint]]s, while [[tendon]]s connect bone to [[muscle]]. Some ligaments limit the mobility of articulations or prevent certain movements altogether.

Capsular ligaments are part of the [[articular capsule]] that surrounds [[synovial joint]]s.  They act as mechanical reinforcements.  Extra-capsular ligaments join in harmony with the other ligaments and provide joint stability.  Intra-capsular ligaments, which are much less common,{{Citation needed|date=November 2010}} also provide stability but permit a far larger range of motion.  [[Cruciate ligament]]s are paired ligaments in the form of a cross.<ref>{{cite book
|title=Cunningham's text-book of anatomy
|author=Daniel John Cunningham
|author1-link=Daniel John Cunningham
|publisher=Oxford Press
|year=1918
|edition=5th
|pages=1593
|url=https://books.google.com/books?id=TdflAHpC8XkC&q=cruciate+ligament&pg=PA346}}</ref>

Ligaments are [[viscoelastic]]. They gradually strain when under tension and return to their original shape when the tension is removed. However, they cannot retain their original shape when extended past a certain point or for a prolonged period of time.<ref>{{Cite journal|last1=R.A.|first1=Hauser|last2=E.E.|first2=Dolan|last3=H.J.|first3=Phillips|last4=A.C.|first4=Newlin|last5=R.E.|first5=Moore|last6=B.A.|first6=Woldin|date=2013-01-23|title=Ligament Injury and Healing: A Review of Current Clinical Diagnostics and Therapeutics|url=https://benthamopen.com/contents/pdf/TOREHJ/TOREHJ-6-1.pdf |journal=The Open Rehabilitation Journal|volume=6|issue=1|pages=5 |doi= 10.2174/1874943701306010001 |doi-access=free}}</ref> This is one reason why [[dislocation (medicine)|dislocated]] joints must be set as quickly as possible: if the ligaments lengthen too much, then the joint will be weakened, becoming prone to future dislocations.  [[Athlete]]s, gymnasts, dancers, and martial artists perform stretching exercises to lengthen their ligaments, making their joints more supple.

The term ''[[Hypermobility (joints)|hypermobility]]'' refers to the characteristic of people with more-elastic ligaments, allowing their joints to stretch and contort further; this is sometimes still called ''double-jointedness''.
[[File:Hypermobility-10.jpg|thumb|Hypermobile finger]]

The consequence of a broken ligament can be instability of the joint. Not all broken ligaments need surgery, but, if surgery is needed to stabilise the joint, the broken ligament can be repaired. [[Granulation tissue|Scar tissue]] may prevent this. If it is not possible to fix the broken ligament, other procedures such as the [[Brunelli procedure]] can correct the instability. Instability of a joint can over time lead to wear of the cartilage and eventually to [[osteoarthritis]].

=== Artificial ligaments ===
One of the most often torn ligaments in the body is the [[anterior cruciate ligament]] (ACL). The ACL is one of the ligaments crucial to knee stability and persons who tear their ACL often undergo reconstructive surgery, which can be done through a variety of techniques and materials.  One of these techniques is the replacement of the ligament with an artificial material. [[Artificial ligament]]s are a synthetic material composed of a polymer, such as polyacrylonitrile fiber, [[polypropylene]], PET (polyethylene terephthalate), or polyNaSS poly (sodium styrene sulfonate).<ref>{{cite journal|vauthors=Lessim S, Migonney V, Thoreux P, Lutomski D, Changotade S |url= https://www.researchgate.net/publication/242018745 |title=PolyNaSS bioactivation of LARS artificial ligament promotes human ligament fibroblast colonisation in vitro|journal=Biomed Mater Eng |volume=23 |issue=4 |date=June 2013 |pages=289–297 |pmid=23798650 |doi=10.3233/BME-130753}}</ref>

=== Examples ===
There are about 900 ligaments in an average adult human body,<ref>{{Cite web |title=Ligament |url=https://www.physio-pedia.com/Ligament |access-date=2023-09-11 |website=Physiopedia |language=en}}</ref><ref>{{Cite web |title=Ligament: Anatomy, Function, Sprain |url=https://my.clevelandclinic.org/health/body/21604-ligament |access-date=2023-09-11 |website=Cleveland Clinic |language=en}}</ref> of which about 25 are listed here.
{|
|
;Head and neck
* [[Cricothyroid ligament]]
* [[Periodontal ligament]]
* [[Suspensory ligament of the lens]]

;Thorax
* [[Phrenoesophageal ligament]]
* [[Suspensory ligament of the breast]]

;Pelvis
* [[Anterior sacroiliac ligament]]
* [[Posterior sacroiliac ligament]]
* [[Sacrotuberous ligament]]
* [[Sacrospinous ligament]]
* [[Inferior pubic ligament]]
* [[Reflex inguinal ligament]]
* [[Superior pubic ligament]]
* [[Suspensory ligament of the clitoris]]
* [[Suspensory ligament of the penis]]
|width=30|
|valign=top|
;Wrist
* [[Palmar radiocarpal ligament]]
* [[Dorsal radiocarpal ligament]]
* [[Ulnar collateral ligament (wrist)|Ulnar collateral ligament]]
* [[Radial collateral ligament (wrist)|Radial collateral ligament]]
* [[Scapholunate ligament]]

;Knee
* [[Anterior cruciate ligament]] 
* [[Fibular collateral ligament|Lateral collateral ligament]] 
* [[Posterior cruciate ligament]] 
* [[Medial collateral ligament]] 
* [[Cranial cruciate ligament]]&nbsp;— [[quadruped]] equivalent of anterior cruciate ligament
* [[Caudal cruciate ligament]]&nbsp;— [[quadruped]] equivalent of posterior cruciate ligament 
* [[Oblique popliteal ligament]]
* [[Patellar ligament]]
|}

==Peritoneal ligaments==
Certain folds of [[peritoneum]] are referred to as ''ligaments''.  Examples include:
* The [[hepatoduodenal ligament]], that surrounds the [[hepatic portal vein]] and other vessels as they travel from the [[duodenum]] to the [[liver]].
* The [[broad ligament of the uterus]], also a fold of peritoneum.

==Fetal remnant ligaments==
Certain tubular structures from the fetal period are referred to as ''ligaments'' after they close up and turn into cord-like structures:{{citation needed|date=February 2017}}

{| class="wikitable"
 ! Fetal || Adult
 |-
 |[[ductus arteriosus]] || [[ligamentum arteriosum]]
 |-
 | extra-[[hepatic]] portion of the fetal left [[umbilical vein]] || [[ligamentum teres hepatis]] (the "round ligament of the liver").
 |-
 | intra-hepatic portion of the fetal left umbilical vein (the [[ductus venosus]]) || [[ligamentum venosum]]
 |-
 | [[Anatomical terms of location#Proximal and distal|distal]] portions of the fetal left and right [[umbilical arteries]] || [[medial umbilical ligaments]]
|}

==See also== 
* [[Ligamentous laxity]]
* [[Broström procedure]]

==References==
{{Reflist}}

{{Commons category|Ligaments}}

{{Joints}}
{{Joints of head and neck}}
{{Joints of upper limbs}}
{{Joints of torso}}
{{Joints of lower limbs}}
{{Abdominopelvic cavity}}
{{Fetal remnant ligaments}}
{{Connective tissue}}
{{Authority control}}

[[Category:Soft tissue]]
[[Category:Skeletal system]]
[[Category:Ligaments| ]]