Joint
| Joint | |
|---|---|
Musculoskeletal system Articular system | |
| Identifiers | |
| Latin | articulus, junctura, articulatio |
| MeSH | D007596 |
| TA98 | A03.0.00.000 |
| TA2 | 1515 |
| FMA | 73023 |
| Anatomical terminology] | |
A joint or articulation (or articular surface) is the connection made between
Classification
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
- monoarticular – concerning one joint
- oligoarticular or pauciarticular – concerning 2–4 joints
- polyarticular – concerning 5 or more joints
Structural classification (binding tissue)
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]
- fibrous joint – joined by dense regular connective tissue that is rich in collagen fibers[9]
- cartilaginous joint – joined by cartilage. There are two types: primary cartilaginous joints composed of hyaline cartilage, and 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.[9]
- facet joint – joint between two articular processes between two vertebrae.[10][11]
Functional classification (movement)
Joints can also be classified functionally according to the type and degree of movement they allow:
- synarthrosis – permits little or no mobility. Most synarthrosis joints are fibrous joints, such as skull sutures. This lack of mobility is important, because the skull bones serve to protect the brain.[13]
- amphiarthrosis – permits slight mobility. Most amphiarthrosis joints are cartilaginous joints. 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.[13]
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
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]
- Simple joint: two articulation surfaces (e.g. 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 (e.g. knee joint)
Anatomical
The joints may be classified anatomically into the following groups:
- Joints of hand
- Elbow joints
- Wrist joints
- Axillary joints
- Sternoclavicular joints
- Vertebral articulations
- Temporomandibular joints
- Sacroiliac joints
- Hip joints
- Knee joints
- 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
Damaging the cartilage of joints (
A joint disorder is termed
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,
History
Etymology
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
- Arthrology
- Cracking joints
- Kinesiology
- Ligament
- Development of joints
References
- ^ ISBN 9780736036825.
- ^ "Articulation definition". eMedicine Dictionary. 30 October 2013. Archived from the original on 31 July 2012. Retrieved 18 November 2013.
- ^ a b c d e f Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw-Hill Connect. Web. p.274
- ISBN 0-443-07168-3.
- S2CID 72038079.
- ^ "Sesamoid Injuries in the Foot – Sesamoiditis Foot | Foot Health Facts - Foot Health Facts". www.foothealthfacts.org. Retrieved 2021-07-04.
- PMID 26380010.
- ^ "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.
- ^ a b Principles of Anatomy & Physiology, 12th Edition, Tortora & Derrickson, Pub: Wiley & Sons
- ^ "Articular Facet". Medilexicon – Medical Dictionary. Archived from the original on August 6, 2016. Retrieved December 19, 2013.
- ^ "Foundational Model of Anatomy". Archived from the original on December 19, 2013. Retrieved December 19, 2013.
- ^ 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.
- ^ ISBN 978-1-951693-42-8. Retrieved 13 May 2023.
- ^ Morton, Samuel George (1849). An Illustrated System of Human Anatomy. p. 119.
- ^ Gray, Henry (1859). Anatomy, descriptive and surgical. p. 136.
- ^ Gray, Henry (1887). Anatomy, descriptive and surgical. p. 220.
- ^ ISBN 9783135333069.
- ^ Armen S Kelikian, Shahan Sarrafian Sarrafian's Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional p. 94
- ^ "Introductory Anatomy: Joints". Retrieved 2008-01-29.
- ^ "Clinical Neuroanatomy and Neuroscience - 6th Edition". www.elsevier.com. Retrieved 2019-03-17.
- ^ 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.
- ^ Lewis, C.T. & Short, C. (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.
- ^ Thompson, Helen. "Switching to Farming Made Human Joint Bones Lighter". Smithsonian Magazine. Smithsonian, 22 December 2014. Retrieved 28 November 2016.
External links
