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{{Short description|Location at which two or more bones make contact}}
{{otheruses}}
{{other uses}}
{{redirect|Articulations|articulations in music|Articulation (music)}}
{{Infobox anatomy
A '''joint''' is the location at which two or more [[bone]]s make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.
| Name = Joint
| Latin = articulus,<br />junctura,<br />articulatio
| Greek =
| Image = Joint.svg
| Caption = Diagram of a typical [[synovial joint]]
| Width = 300
| Image2 = Gray298.png
| Caption2 = Depiction of an [[intervertebral disc]], a [[cartilaginous joint]]
| Precursor =
| System = [[Musculoskeletal system]]<br />Articular system
| Artery =
| Vein =
| Nerve =
| Lymph =
}}
A '''joint''' or '''articulation''' (or '''articular surface''') is the connection made between [[bone]]s, [[ossicles]], or other hard structures in the body which link an animal's [[skeletal system]] into a functional whole.<ref name="Whiting2006p40">{{cite book |last1=Whiting |first1=William Charles |last2=Rugg |first2=Stuart |year=2006 |title=Dynamic Human Anatomy |volume=10 |url=https://books.google.com/books?id=ylyAXBPno2IC&pg=PA40 |pages=40|publisher=Human Kinetics |isbn=9780736036825 }}</ref><ref>{{cite web|url=http://www.emedicinehealth.com/script/main/art.asp?articlekey=8746|title=Articulation definition|publisher=eMedicine Dictionary|date=30 October 2013|access-date=18 November 2013|archive-date=31 July 2012|archive-url=https://web.archive.org/web/20120731092044/http://www.emedicinehealth.com/script/main/art.asp?articlekey=8746|url-status=dead}}</ref><ref name="Saladinp274">Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw-Hill Connect. Web. [http://connect.mheducation.com/connect/hmEBook.do?setTab=sectionTabs p.274]</ref> They are constructed to allow for different degrees and types of movement. Some joints, such as the [[knee]], [[elbow]], and [[shoulder]], are self-lubricating, almost frictionless, and are able to withstand compression and maintain heavy loads while still executing smooth and precise movements.<ref name="Saladinp274"/> Other joints such as [[suture (joint)|sutures]] between the bones of the [[skull]] permit very little movement (only during birth) in order to protect the brain and the [[sense organ]]s.<ref name="Saladinp274"/> The connection between a tooth and the [[jawbone]] is also called a joint, and is described as a fibrous joint known as a [[gomphosis]]. Joints are classified both structurally and functionally.<ref name="isbn0-443-07168-3">{{cite book|last1=Standring|first1=Susan|title=Gray's anatomy : the anatomical basis of clinical practice.|date=2006|publisher=Elsevier Churchill Livingstone|location=Edinburgh|isbn=0-443-07168-3|page=[https://archive.org/details/graysanatomyanat0000unse/page/38 38]|edition=39th|url=https://archive.org/details/graysanatomyanat0000unse/page/38}}</ref>

Joints play a vital role in the human body, contributing to movement, stability, and overall function. They are essential for mobility and flexibility, connecting bones and facilitating a wide range of motions, from simple bending and stretching to complex actions like running and jumping. Beyond enabling movement, joints provide structural support and stability to the skeleton, helping to maintain posture, balance, and the ability to bear weight during daily activities.

The clinical significance of joints is highlighted by common disorders that affect their health and function. '''Osteoarthritis''', a degenerative joint disease, involves the breakdown of cartilage, leading to pain, stiffness, and reduced mobility. '''Rheumatoid arthritis''', an autoimmune disorder, causes chronic inflammation in the joints, often resulting in swelling, pain, and potential deformity. Another prevalent condition, '''gout''', arises from the accumulation of uric acid crystals in the joints, triggering severe pain and inflammation.

Joints also hold diagnostic importance, as their condition can indicate underlying health issues. Symptoms such as joint pain and swelling may signal inflammatory diseases, infections, or metabolic disorders. Effective treatment and management of joint-related conditions often require a multifaceted approach, including physical therapy, medications, lifestyle changes, and, in severe cases, surgical interventions. Preventive care, such as regular exercise, a balanced diet, and avoiding excessive strain, is critical for maintaining joint health, preventing disorders, and improving overall quality of life.


==Classification==
==Classification==
Joints are mainly classified structurally and functionally. Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications. In example, the highly mobile diarthroses are universally synovial joints (and in practice the two terms are used interchangeably) though the first term refers to the functional classification and the second to the structural classification.


The number of joints depends on if [[Sesamoid bone|sesamoids]] are included, age of the human and the definition of joints. However, the number of sesamoids is the same in most people with variations being rare.<ref>{{Cite journal|last=Wood|first=V. E.|date=October 1984|title=The sesamoid bones of the hand and their pathology|url=https://pubmed.ncbi.nlm.nih.gov/6512360/#:~:text=Most%20people%20have%20five%20sesamoid,finger%20on%20the%20ulnar%20side.|journal=Journal of Hand Surgery (Edinburgh, Scotland)|volume=9|issue=3|pages=261–264|doi=10.1016/0266-7681(84)90038-x|issn=0266-7681|pmid=6512360|s2cid=72038079}}</ref><ref>{{Cite web|title=Sesamoid Injuries in the Foot – Sesamoiditis Foot {{!}} Foot Health Facts - Foot Health Facts|url=https://www.foothealthfacts.org/conditions/sesamoid-injuries-in-the-foot|access-date=2021-07-04|website=www.foothealthfacts.org}}</ref><ref>{{Cite journal|last1=Chen|first1=Wei|last2=Cheng|first2=Jiaxiang|last3=Sun|first3=Ran|last4=Zhang|first4=Zekun|last5=Zhu|first5=Yanbin|last6=Ipaktchi|first6=Kyros|last7=Zhang|first7=Yingze|date=2015-07-15|title=Prevalence and variation of sesamoid bones in the hand: a multi-center radiographic study|journal=International Journal of Clinical and Experimental Medicine|volume=8|issue=7|pages=11721–11726|issn=1940-5901|pmc=4565393|pmid=26380010}}</ref>
Terms ending in the [[suffix]] -sis are singlular and refer to just one joint, while -ses is the suffix for pluralization.


Joints are mainly classified structurally and functionally. Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications.
=== Structural classification ===
[[Image:Gray298.png|thumb|right|Depiction of an intervertebral disk, a cartilaginous joint.]]
Structural classification names and divides joints according to how the bones are connected to each other. There are three structural classifications of joints: fibrous/immovable, cartilaginous and synovial:


===Clinical, numerical classification===
====Fibrous/Immovable==== <!-- Fibrous joint redirects here-->
*monoarticular – concerning one joint
Fibrous/Immovable bones are connected by [[Fibrous connective tissue|dense connective tissue]], consisting mainly of [[collagen]]. The fibrous joints are further divided into three types:
*oligoarticular or pauciarticular – concerning 2–4 joints
*'''Sutures''' are found between bones of the [[skull]]. In fetal skulls the sutures are wide to allow slight movement during birth. They later become rigid (synarthrodial).
*polyarticular – concerning 5 or more joints
*'''Syndesmosis''' are found between long bones of the body, such as the [[radius (bone)|radius]] and [[ulna]] in forearm and the [[fibula]] and [[tibia]] in leg. Unlike other fibrous joints, syndesmoses are moveable (amphiarthrodial), albeit not to such degree as synovial joints.
*'''Gomphosis''' is a joint between the root of a [[tooth]] and the [[Dental alveolus|sockets]] in the [[maxilla]] or [[mandible]].


=== Structural classification (binding tissue)===
====Cartilaginous==== <!--Cartilaginous joint redirects here-->
[[File:Structural Classification of Joints.jpg|thumb|300x300px|Types of joints based upon their structure (L to R): cartilaginous joint, fibrous joint, and synovial joint.]]
Cartilaginous bones are connected entirely by [[cartilage]]. Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint. An example would be the joint between the [[manubrium]] and the [[sternum]]. Cartilaginous joints also forms the [[Bone#Formation|growth regions]] of immature long bones and the [[intervertebral disc]]s of the [[vertebral column|spinal column]].
Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other.<ref name="Whiting2006p40"/> There are four structural classifications of joints:<ref name="umich2010ClByTiss">{{cite web |url=http://anatomy.med.umich.edu/modules/joints_module/joints_03.html
*'''Primary cartilaginous joints''' - Known as "synchondroses". Bones are connected by hyaline cartilage or fibrocartilage, sometimes occurring between ossification centers. This cartilage may ossify with age. Examples in humans are the joint between the first rib and the manubrium of the sternum, and the "growth plates" between ossification centers in long bones. These joints usually allow no movement, or minimal movement in the case of the manubriosternal and first manubriocostal joints.
|archive-url=https://web.archive.org/web/20110608081814/http://anatomy.med.umich.edu/modules/joints_module/joints_03.html |archive-date=2011-06-08 |title=Introduction to Joints (3) – Joints – Classification by Tissue Joining Bones |access-date=2008-01-29 | publisher=anatomy.med.umich.edu}}</ref>
*'''Secondary cartilaginous joints''' - Known as "symphyses". Fibrocartilaginous joints, usually occurring in the midline. Examples in human anatomy would be the intervertebral discs, and the pubic symphysis. These joints allow a little movement.
* [[fibrous joint]] – joined by dense regular connective tissue that is rich in collagen fibers<ref name="anatomical">Principles of Anatomy & Physiology, 12th Edition, Tortora & Derrickson, Pub: Wiley & Sons</ref>
* [[cartilaginous joint]] – joined by [[cartilage]]. There are two types: [[Cartilaginous joint#Primary cartilaginous joints|primary cartilaginous joints]] composed of [[hyaline cartilage]], and [[Cartilaginous joint#Secondary cartilaginous joints|secondary cartilaginous joints]] composed of hyaline cartilage covering the articular surfaces of the involved bones with [[fibrocartilage]] connecting them.
* [[synovial joint]] – not directly joined – the bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule that is normally associated with accessory ligaments.<ref name="anatomical"/>
* [[facet joint]] – joint between two articular [[process (anatomy)|processes]] between two vertebrae.<ref name="Medilexicon">{{cite web | url=http://www.medilexicon.com/medicaldictionary.php?t=31339 | publisher=Medilexicon – Medical Dictionary | title=Articular Facet | access-date=December 19, 2013 | archive-date=August 6, 2016 | archive-url=https://web.archive.org/web/20160806005701/http://www.medilexicon.com/medicaldictionary.php?t=31339 | url-status=dead }}</ref><ref>{{cite web | url=http://www.ontobee.org/browser/index.php?keywords=Articular+facet&Submit2=Search+terms&o=FMA | title=Foundational Model of Anatomy | access-date=December 19, 2013 | url-status=dead | archive-url=https://web.archive.org/web/20131219182622/http://www.ontobee.org/browser/index.php?keywords=Articular+facet&Submit2=Search+terms&o=FMA | archive-date=December 19, 2013 }}</ref>


===Functional classification (movement)===
OH MY GOD UR UGLY
Joints can also be classified functionally according to the type and degree of movement they allow:<ref name="Whiting2006p40"/><ref name="umich2010ClByMov">{{cite web |url=http://anatomy.med.umich.edu/modules/joints_module/joints_02.html |archive-url=https://web.archive.org/web/20110718163549/http://anatomy.med.umich.edu/modules/joints_module/joints_02.html |archive-date=2011-07-18 |title=Introduction to Joints (2) – Joints – Classification by Movement |access-date=2012-10-06 | publisher=anatomy.med.umich.edu}}</ref> Joint movements are described with reference to the basic [[anatomical planes]].<ref name="Saladinp274"/>
GET OFF THIS EBSITE
* [[synarthrosis]] – permits little or no mobility. Most synarthrosis joints are [[fibrous joint]]s, such as skull sutures. This lack of mobility is important, because the skull bones serve to protect the brain.<ref name="openstax">{{cite book|title=- Anatomy and Physiology|author=J. Gordon Betts |display-authors=et al|publisher=OpenStax|chapter=9.1 Classification of Joints|date=20 April 2022 |chapter-url=https://openstax.org/books/anatomy-and-physiology-2e/pages/9-1-classification-of-joints|access-date=13 May 2023|isbn=978-1-951693-42-8}}</ref>
* [[amphiarthrosis]] – permits slight mobility. Most amphiarthrosis joints are [[cartilaginous joint]]s. An example is the [[intervertebral disc]]. Individual intervertebral discs allow for small movements between adjacent vertebrae, but when added together, the vertebral column provides the flexibility that allows the body to twist, or bend to the front, back, or side.<ref name="openstax"/>
* [[synovial joint]] (also known as a ''diarthrosis'') – freely movable.<ref name="Whiting2006p40"/><ref name="umich2010ClByMov"/> Synovial joints can in turn be classified into six groups according to the type of movement they allow: [[plane joint]], [[ball and socket joint]], [[hinge joint]], [[pivot joint]],<ref name="Morton1849p119">{{cite book |author-link=Samuel George Morton |first1=Samuel George |last1=Morton |year=1849 |title=An Illustrated System of Human Anatomy |url=https://archive.org/details/61120330R.nlm.nih.gov/page/n128 |page=119}}</ref><ref name="Gray1859p136">{{cite book |author-link=Henry Gray |first=Henry |last=Gray |year=1859 |title=Anatomy, descriptive and surgical |url=https://archive.org/details/06220300R.nlm.nih.gov/page/n169 |page=136}}</ref> [[condyloid joint]] and [[saddle joint]].<ref name="Gray1887p220">{{cite book |author-link=Henry Gray |first=Henry |last=Gray |year=1887 |title=Anatomy, descriptive and surgical |url=https://archive.org/stream/anatodescripti00grayrich#page/220/mode/2up |page=220}}</ref>
Joints can also be classified, according to the number of axes of movement they allow, into nonaxial (gliding, as between the proximal ends of the ulna and radius), monoaxial (uniaxial), biaxial and [[Multiaxial joint|multiaxial]].<ref name="Platzer2008p28">{{cite book |last1=Platzer |first1=Werner |year=2008 |title=Color Atlas of Human Anatomy |volume=1 |url=https://books.google.com/books?id=T9bb4T422j8C&pg=PA28 |page=28|publisher=Thieme |isbn=9783135333069 }}</ref> Another classification is according to the [[Degrees of freedom (mechanics)|degrees of freedom]] allowed, and distinguished between joints with one, two or three degrees of freedom.<ref name="Platzer2008p28"/> A further classification is according to the number and shapes of the articular surfaces: flat, concave and convex surfaces.<ref name="Platzer2008p28"/> Types of articular surfaces include [[wikt:trochlear|trochlear]] surfaces.<ref>Armen S Kelikian, Shahan Sarrafian [https://books.google.com/books?id=I8h6bDR0SLMC&pg=PA94 ''Sarrafian's Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional''] p.&nbsp;94</ref>


===Biomechanical classification===
I LOVE PANCAKES
Joints can also be classified based on their anatomy or on their biomechanical properties. According to the anatomic classification, joints are subdivided into ''simple'' and ''compound'', depending on the number of bones involved, and into ''complex'' and ''combination'' joints:<ref name="titleIntroductory Anatomy: Joints">{{cite web |url=http://www.leeds.ac.uk/chb/lectures/anatomy4.html |title=Introductory Anatomy: Joints |access-date=2008-01-29 |archive-date=2008-01-18 |archive-url=https://web.archive.org/web/20080118135754/http://www.leeds.ac.uk/chb/lectures/anatomy4.html |url-status=dead }}</ref>
# Simple joint: two articulation surfaces (e.g. [[shoulder joint]], [[hip joint]])
# Compound joint: three or more articulation surfaces (e.g. [[radiocarpal joint]])
# Complex joint: two or more articulation surfaces and an [[articular disc]] or [[meniscus (anatomy)|meniscus]] (e.g. [[knee|knee joint]])


===Anatomical=== <!--joint groups redirects here-->
BUM
[[File:Joints 1 -- Smart-Servier.png|thumb|Joints of the human body]]
The joints may be classified anatomically into the following groups:
# [[Joints of hand]]
# [[Elbow|Elbow joints]]
# [[Wrist|Wrist joints]]
# [[Axillary joints]]
# [[Sternoclavicular joint]]s
# [[Vertebral articulation]]s
# [[Temporomandibular joint]]s
# [[Sacroiliac joint]]s
# [[Hip joint]]s
# [[Knee|Knee joint]]s
# [[Articulations of foot]]


[[Axon|Unmyelinated nerve fibers]] are abundant in joint capsules and ligaments, as well as in the outer part of intra-articular menisci. These nerve fibers are responsible for pain perception when a joint is strained.<ref>{{Cite web|url=https://www.elsevier.com/books/clinical-neuroanatomy-and-neuroscience/mtui/978-0-7020-3738-2|title=Clinical Neuroanatomy and Neuroscience - 6th Edition|website=www.elsevier.com|access-date=2019-03-17}}</ref>
===Functional classification ===
[[Image:Illu synovial joint.jpg|thumb|right|Diagram of a synovial (diarthrosis) joint.]]
Joints can also be classified functionally, by the degree of mobility they allow, into synarthroses, amphiarthroses and diarthroses:


==Clinical significance==
====Synarthrosis====
{{Further|Arthropathy|Arthritis|Joint replacement}}
Synarthroses permit little or no mobility. Most synarthrosis joints are fibrous. They can be categorised by how the two bones are joined together:
Damaging the cartilage of joints ([[articular cartilage]]) or the bones and muscles that stabilize the joints can lead to [[joint dislocation]]s and osteoarthritis. Swimming is a great way to exercise the joints with minimal damage.<ref name="Saladinp274"/>
* ''Synchondroses'' are joints where the two bones are connected by a piece of cartilage.
* ''Synostoses'' are where two bones that are initially separted eventually fuse together, essentially becoming one bone. In humans the plates of the cranium fuse together as a child approaches adulthood. Children whose craniums fuse too early may suffer deformities and brain damage as the skull does not expand properly to accommodate the growing brain, a condition known as [[craniostenosis]].


A joint disorder is termed [[arthropathy]], and when involving [[inflammation]] of one or more joints the disorder is called [[arthritis]]. Most joint disorders involve arthritis, but joint damage by external [[physical trauma]] is typically not termed arthritis.
====Amphiarthrosis====
{{Main|Amphiarthrosis}}
Amphiarthroses permit slight mobility. The two bone surfaces at the joint are both covered in hyaline cartilage and joined by strands of [[fibrocartilage]]. Most amphiarthrosis joints are cartilaginous.


Arthropathies are called ''polyarticular'' (multiarticular) when involving many joints and ''monoarticular'' when involving only a single joint.
====Diarthrosis====
{{Seealso|Synovial joint}}
Diarthroses permit a variety of movements (e.g. [[flexion]], [[anatomical terms of motion|adduction, pronation]]). Only synovial joints are diarthrodial. They can be divided into six classes:


Arthritis is the leading cause of disability in people over the age of 55. There are many different forms of arthritis, each of which has a different cause. The most common form of arthritis, [[osteoarthritis]] (also known as degenerative joint disease), occurs following trauma to the joint, following an [[infection]] of the joint or simply as a result of aging and the deterioration of articular cartilage. Furthermore, there is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis. Other forms of arthritis are [[rheumatoid arthritis]] and [[psoriatic arthritis]], which are [[autoimmune disorder|autoimmune diseases]] in which the body is attacking itself. [[Septic arthritis]] is caused by joint infection. [[Gout|Gouty arthritis]] is caused by deposition of [[uric acid]] crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout that is caused by the formation of rhomboidal-shaped crystals of [[calcium pyrophosphate]]. This form of gout is known as [[Chondrocalcinosis|pseudogout]].
* ''1. [[Ball and socket joint|Ball and Socket]]'' - such as the shoulder or the hip and [[femur]].
* ''2. [[Hinge joint|Hinge]]'' - such as the elbow.
* ''3. [[Pivot joint|Pivot]]'' - such as the [[Radius (bone)|radius]] and [[ulna]].
* ''4. [[Condyloid joint|Condyloid (or ellipsoidal)]]'' - such as the wrist between radius and [[carpals]], or [[knee]]
* ''5. [[Saddle joint|Saddle]]'' - such as the joint between carpal thumbs and [[metacarpals]].
* ''6. [[Gliding joint|Gliding]]'' - such as between the carpals.


[[Temporomandibular joint syndrome]] (TMJ) involves the jaw joints and can cause facial pain, clicking sounds in the jaw, or limitation of jaw movement, to name a few symptoms. It is caused by psychological tension and misalignment of the jaw ([[malocclusion]]), and may be affecting as many as 75 million Americans.<ref name="Saladinp274"/>
===Biomechanical classification===
Joints can also be classified based on their anatomy or on their biomechanic properties. According to the anatomic classification, joints are subdivided into ''simple'' and ''compound,'' depending on the number of bones involved, and into ''complex'' and ''combination'' joints.
# Simple Joint: 2 articulation surfaces (eg. shoulder joint, hip joint)
# Compound Joint: 3 or more articulation surfaces (eg. radiocarpal joint)
# Complex Joint: 3 or more articulation surfaces AND an articular disc


==Arthritis==
==History==
{{Main|Arthritis}}
Arthritis and direct [[physical trauma]] to a joint are the causes of joint damage. Arthritis is a group of conditions where there is damage caused to the [[joint]]s of the body. Arthritis is the leading cause of disability in people over the age of 55.


===Etymology===
There are many different forms of arthritis, each of which has a different cause. The most common form of arthritis, [[osteoarthritis]] (also known as degenerative joint disease) occurs following trauma to the joint, following an infection of the joint or simply as a result of aging. Furthermore, there is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis. Other forms of arthritis are [[rheumatoid arthritis]] and [[psoriatic arthritis]], which are [[autoimmune disorder|autoimmune diseases]] in which the body is attacking itself. [[Septic arthritis]] is caused by joint [[infection]]. [[gout|Gouty arthritis]] is caused by deposition of [[uric acid]] crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout that is caused by the formation of rhomboidal shaped crystals of calcium pyrophosphate. This form of gout is known as [[Calcium pyrophosphate deposition disease|pseudogout]].
The English word ''joint'' is a past participle of the verb ''join'', and can be read as ''joined''.<ref name="Klein1971">Klein, E. (1971). A comprehensive etymological dictionary of the English language. Dealing with the origin of words and their sense development thus illustration the history of civilization and culture. Amsterdam: Elsevier Science B.V.</ref> Joint is derived from Latin ''iunctus'',<ref name="Klein1971"/> past participle of the Latin verb ''iungere'', join, unite, connect, attach.<ref name="Lewis & Short">Lewis, C.T. & Short, C. (1879). ''A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary.'' Oxford: Clarendon Press.</ref>


The English term ''articulation'' is derived from Latin ''articulatio''.<ref name="Klein1971"/>
== See also ==

{{commonscat|joints}}
Humans have also developed lighter, more fragile joint bones over time due to the decrease in physical activity compared to thousands of years ago.<ref name="Thompson2014">Thompson, Helen. "[http://www.smithsonianmag.com/science-nature/switching-farming-made-human-joint-bones-lighter-180953711/ Switching to Farming Made Human Joint Bones Lighter]". ''Smithsonian Magazine''. Smithsonian, 22 December 2014. Retrieved 28 November 2016.</ref>
* [[Arthrology]], the science concerned with the anatomy, function, dysfunction and treatment of joints.

* [[Kinesiology]], the study of musculoskeletal movements.
==See also==
* [[Replacement joint]]

* [[Arthrology]]
* [[Cracking joints]]
* [[Kinesiology]]
* [[Ligament]]
* [[Development of joints]]

==References==
{{reflist}}


==External links==
==External links==
{{Commons category|Joints|lcfirst=yes}}
* [http://www.shockfamily.net/skeleton/JOINTS.HTML Illustration of synovial joints at shockfamily.net]
* [http://www.sports-db.com/home/information/joints.html Synovial joints Illustrations and Classification]
* [http://www.sports-db.com/home/information/joints.html Synovial joints Illustrations and Classification]


{{Human systems and organs}}
{{Joints}}
{{Joints}}
{{Cranial fibrous joints}}
{{Joints of head and neck}}
{{Joints of head and neck}}
{{Joints of upper limbs}}
{{Joints of torso}}
{{Joints of torso}}
{{Joints of upper limbs}}
{{Joints of lower limbs}}
{{Joints of lower limbs}}


{{Authority control}}
[[Category:Skeletal system]]


[[br:Mell]]
[[Category:Joints| ]]
[[Category:Skeletal system]]
[[ca:Articulació (anatomia)]]
[[cs:Kloub]]
[[da:Led (anatomi)]]
[[de:Gelenk]]
[[es:Articulación (anatomía)]]
[[eo:Artiko]]
[[fr:Articulation (anatomie)]]
[[ga:Alt (anatamaíocht)]]
[[gd:Alt (corp)]]
[[hr:Zglob]]
[[id:Sendi]]
[[it:Articolazione]]
[[he:מפרק]]
[[lt:Sąnarys]]
[[nl:Gewricht]]
[[ja:関節]]
[[pl:Staw (anatomia)]]
[[pt:Articulação]]
[[ru:Сустав]]
[[simple:Joint]]
[[sk:Kĺb (anatómia)]]
[[sr:Зглоб]]
[[fi:Nivel]]
[[sv:Led]]
[[uk:Суглоб]]
[[zh:关节]]

Latest revision as of 03:56, 29 November 2024

For other uses, see Joint (disambiguation).
Joint
Diagram of a typical synovial joint
Depiction of an intervertebral disc, a cartilaginous joint
Details
SystemMusculoskeletal system
Articular system
Identifiers
Latinarticulus,
junctura,
articulatio
MeSHD007596
TA98A03.0.00.000
TA21515
FMA7490
Anatomical terminology

A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.[1][2][3] They are constructed to allow for different degrees and types of movement. Some joints, such as the knee, elbow, and shoulder, are self-lubricating, almost frictionless, and are able to withstand compression and maintain heavy loads while still executing smooth and precise movements.[3] Other joints such as sutures between the bones of the skull permit very little movement (only during birth) in order to protect the brain and the sense organs.[3] The connection between a tooth and the jawbone is also called a joint, and is described as a fibrous joint known as a gomphosis. Joints are classified both structurally and functionally.[4]

Joints play a vital role in the human body, contributing to movement, stability, and overall function. They are essential for mobility and flexibility, connecting bones and facilitating a wide range of motions, from simple bending and stretching to complex actions like running and jumping. Beyond enabling movement, joints provide structural support and stability to the skeleton, helping to maintain posture, balance, and the ability to bear weight during daily activities.

The clinical significance of joints is highlighted by common disorders that affect their health and function. Osteoarthritis, a degenerative joint disease, involves the breakdown of cartilage, leading to pain, stiffness, and reduced mobility. Rheumatoid arthritis, an autoimmune disorder, causes chronic inflammation in the joints, often resulting in swelling, pain, and potential deformity. Another prevalent condition, gout, arises from the accumulation of uric acid crystals in the joints, triggering severe pain and inflammation.

Joints also hold diagnostic importance, as their condition can indicate underlying health issues. Symptoms such as joint pain and swelling may signal inflammatory diseases, infections, or metabolic disorders. Effective treatment and management of joint-related conditions often require a multifaceted approach, including physical therapy, medications, lifestyle changes, and, in severe cases, surgical interventions. Preventive care, such as regular exercise, a balanced diet, and avoiding excessive strain, is critical for maintaining joint health, preventing disorders, and improving overall quality of life.

Classification

[edit]

The number of joints depends on if sesamoids are included, age of the human and the definition of joints. However, the number of sesamoids is the same in most people with variations being rare.[5][6][7]

Joints are mainly classified structurally and functionally. Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications.

Clinical, numerical classification

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  • monoarticular – concerning one joint
  • oligoarticular or pauciarticular – concerning 2–4 joints
  • polyarticular – concerning 5 or more joints

Structural classification (binding tissue)

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Types of joints based upon their structure (L to R): cartilaginous joint, fibrous joint, and synovial joint.

Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other.[1] There are four structural classifications of joints:[8]

Functional classification (movement)

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Joints can also be classified functionally according to the type and degree of movement they allow:[1][12] Joint movements are described with reference to the basic anatomical planes.[3]

Joints can also be classified, according to the number of axes of movement they allow, into nonaxial (gliding, as between the proximal ends of the ulna and radius), monoaxial (uniaxial), biaxial and multiaxial.[17] Another classification is according to the degrees of freedom allowed, and distinguished between joints with one, two or three degrees of freedom.[17] A further classification is according to the number and shapes of the articular surfaces: flat, concave and convex surfaces.[17] Types of articular surfaces include trochlear surfaces.[18]

Biomechanical classification

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Joints can also be classified based on their anatomy or on their biomechanical properties. According to the anatomic classification, joints are subdivided into simple and compound, depending on the number of bones involved, and into complex and combination joints:[19]

  1. Simple joint: two articulation surfaces (e.g. shoulder joint, hip joint)
  2. Compound joint: three or more articulation surfaces (e.g. radiocarpal joint)
  3. Complex joint: two or more articulation surfaces and an articular disc or meniscus (e.g. knee joint)

Anatomical

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Joints of the human body

The joints may be classified anatomically into the following groups:

  1. Joints of hand
  2. Elbow joints
  3. Wrist joints
  4. Axillary joints
  5. Sternoclavicular joints
  6. Vertebral articulations
  7. Temporomandibular joints
  8. Sacroiliac joints
  9. Hip joints
  10. Knee joints
  11. Articulations of foot

Unmyelinated nerve fibers are abundant in joint capsules and ligaments, as well as in the outer part of intra-articular menisci. These nerve fibers are responsible for pain perception when a joint is strained.[20]

Clinical significance

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Further information: Arthropathy, Arthritis, and Joint replacement

Damaging the cartilage of joints (articular cartilage) or the bones and muscles that stabilize the joints can lead to joint dislocations and osteoarthritis. Swimming is a great way to exercise the joints with minimal damage.[3]

A joint disorder is termed arthropathy, and when involving inflammation of one or more joints the disorder is called arthritis. Most joint disorders involve arthritis, but joint damage by external physical trauma is typically not termed arthritis.

Arthropathies are called polyarticular (multiarticular) when involving many joints and monoarticular when involving only a single joint.

Arthritis is the leading cause of disability in people over the age of 55. There are many different forms of arthritis, each of which has a different cause. The most common form of arthritis, osteoarthritis (also known as degenerative joint disease), occurs following trauma to the joint, following an infection of the joint or simply as a result of aging and the deterioration of articular cartilage. Furthermore, there is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis. Other forms of arthritis are rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases in which the body is attacking itself. Septic arthritis is caused by joint infection. Gouty arthritis is caused by deposition of uric acid crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout that is caused by the formation of rhomboidal-shaped crystals of calcium pyrophosphate. This form of gout is known as pseudogout.

Temporomandibular joint syndrome (TMJ) involves the jaw joints and can cause facial pain, clicking sounds in the jaw, or limitation of jaw movement, to name a few symptoms. It is caused by psychological tension and misalignment of the jaw (malocclusion), and may be affecting as many as 75 million Americans.[3]

History

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Etymology

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The English word joint is a past participle of the verb join, and can be read as joined.[21] Joint is derived from Latin iunctus,[21] past participle of the Latin verb iungere, join, unite, connect, attach.[22]

The English term articulation is derived from Latin articulatio.[21]

Humans have also developed lighter, more fragile joint bones over time due to the decrease in physical activity compared to thousands of years ago.[23]

See also

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References

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  1. ^ a b c d Whiting, William Charles; Rugg, Stuart (2006). Dynamic Human Anatomy. Vol. 10. Human Kinetics. p. 40. ISBN 9780736036825.
  2. ^ "Articulation definition". eMedicine Dictionary. 30 October 2013. Archived from the original on 31 July 2012. Retrieved 18 November 2013.
  3. ^ a b c d e f Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw-Hill Connect. Web. p.274
  4. ^ Standring, Susan (2006). Gray's anatomy : the anatomical basis of clinical practice (39th ed.). Edinburgh: Elsevier Churchill Livingstone. p. 38. ISBN 0-443-07168-3.
  5. ^ Wood, V. E. (October 1984). "The sesamoid bones of the hand and their pathology". Journal of Hand Surgery (Edinburgh, Scotland). 9 (3): 261–264. doi:10.1016/0266-7681(84)90038-x. ISSN 0266-7681. PMID 6512360. S2CID 72038079.
  6. ^ "Sesamoid Injuries in the Foot – Sesamoiditis Foot | Foot Health Facts - Foot Health Facts". www.foothealthfacts.org. Retrieved 2021-07-04.
  7. ^ Chen, Wei; Cheng, Jiaxiang; Sun, Ran; Zhang, Zekun; Zhu, Yanbin; Ipaktchi, Kyros; Zhang, Yingze (2015-07-15). "Prevalence and variation of sesamoid bones in the hand: a multi-center radiographic study". International Journal of Clinical and Experimental Medicine. 8 (7): 11721–11726. ISSN 1940-5901. PMC 4565393. PMID 26380010.
  8. ^ "Introduction to Joints (3) – Joints – Classification by Tissue Joining Bones". anatomy.med.umich.edu. Archived from the original on 2011-06-08. Retrieved 2008-01-29.
  9. ^ a b Principles of Anatomy & Physiology, 12th Edition, Tortora & Derrickson, Pub: Wiley & Sons
  10. ^ "Articular Facet". Medilexicon – Medical Dictionary. Archived from the original on August 6, 2016. Retrieved December 19, 2013.
  11. ^ "Foundational Model of Anatomy". Archived from the original on December 19, 2013. Retrieved December 19, 2013.
  12. ^ a b "Introduction to Joints (2) – Joints – Classification by Movement". anatomy.med.umich.edu. Archived from the original on 2011-07-18. Retrieved 2012-10-06.
  13. ^ a b J. Gordon Betts; et al. (20 April 2022). "9.1 Classification of Joints". - Anatomy and Physiology. OpenStax. ISBN 978-1-951693-42-8. Retrieved 13 May 2023.
  14. ^ Morton, Samuel George (1849). An Illustrated System of Human Anatomy. p. 119.
  15. ^ Gray, Henry (1859). Anatomy, descriptive and surgical. p. 136.
  16. ^ Gray, Henry (1887). Anatomy, descriptive and surgical. p. 220.
  17. ^ a b c Platzer, Werner (2008). Color Atlas of Human Anatomy. Vol. 1. Thieme. p. 28. ISBN 9783135333069.
  18. ^ Armen S Kelikian, Shahan Sarrafian Sarrafian's Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional p. 94
  19. ^ "Introductory Anatomy: Joints". Archived from the original on 2008-01-18. Retrieved 2008-01-29.
  20. ^ "Clinical Neuroanatomy and Neuroscience - 6th Edition". www.elsevier.com. Retrieved 2019-03-17.
  21. ^ a b c Klein, E. (1971). A comprehensive etymological dictionary of the English language. Dealing with the origin of words and their sense development thus illustration the history of civilization and culture. Amsterdam: Elsevier Science B.V.
  22. ^ Lewis, C.T. & Short, C. (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.
  23. ^ Thompson, Helen. "Switching to Farming Made Human Joint Bones Lighter". Smithsonian Magazine. Smithsonian, 22 December 2014. Retrieved 28 November 2016.
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