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. 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. 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 . 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.
16-515: The knuckles are the joints of the fingers . The word is cognate to similar words in other Germanic languages, such as the Dutch "knokkel" (knuckle) or German "Knöchel" (ankle), i.e., Knöchlein , the diminutive of the German word for bone ( Knochen ). Anatomically, it is said that the knuckles consist of the metacarpophalangeal (MCP) and interphalangeal (IP) joints of the finger. The knuckles at
32-699: 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
48-602: A gas bubble forms in the synovial fluid that bathes the joint. Despite this evidence, many still believe it to be caused by synovial fluid filling the vacuum left by the joint's displacement. In 2009, Donald L Unger was awarded the Ig Nobel for Medicine for his informal experiment with knuckle cracking. For 50 years, he cracked the knuckles of one hand while not cracking the knuckles of the other during that time. He self-reported no issues with arthritis on either hand. [REDACTED] This article incorporates text from
64-475: A joint is strained. 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. 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
80-408: 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. The number of joints depends on if sesamoids are included, age of the human and
96-399: A publication now in the public domain : Chisholm, Hugh , ed. (1911). " Knuckle ". Encyclopædia Britannica . Vol. 15 (11th ed.). Cambridge University Press. p. 883. Joint 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
112-419: 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 ,
128-446: 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
144-459: 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
160-433: The anatomic classification, joints are subdivided into simple and compound , depending on the number of bones involved, and into complex and combination joints: The joints may be classified anatomically into the following groups: 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
176-436: The base of the fingers may be referred to as the 1st or major knuckles while the knuckles at the midfinger are known as the 2nd and 3rd, or minor, knuckles. However, the ordinal terms are used inconsistently and may refer to any of the knuckles. The physical mechanism behind the popping or cracking sound heard when cracking joints such as knuckles has recently been elucidated by cine MRI to be caused by tribonucleation as
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#1732790829254192-412: The definition of joints. However, the number of sesamoids is the same in most people with variations being rare. 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
208-501: 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. The English word joint is a past participle of the verb join , and can be read as joined . Joint is derived from Latin iunctus , past participle of the Latin verb iungere , join, unite, connect, attach. The English term articulation
224-410: 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
240-610: 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 . Another classification is according to the degrees of freedom allowed, and distinguished between joints with one, two or three degrees of freedom. A further classification is according to the number and shapes of the articular surfaces: flat, concave and convex surfaces. Types of articular surfaces include trochlear surfaces. Joints can also be classified based on their anatomy or on their biomechanical properties. According to
256-450: The two types of classifications. Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other. There are four structural classifications of joints: Joints can also be classified functionally according to the type and degree of movement they allow: Joint movements are described with reference to the basic anatomical planes . Joints can also be classified, according to
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