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.
30-507: 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
60-418: A coronal section, and likewise a coronal section with respect to the body (i.e. dividing ventral from dorsal) in a rat brain is referred to as transverse . This preserves the comparison with the human brain, whose length axis in rough approximation is rotated with respect to the body axis by 90 degrees in the ventral direction. It implies that the planes of the brain are not necessarily the same as those of
90-699: 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
120-447: A dorsal ( pontine or rhombic flexure ) at the midst of the hindbrain, behind the cerebellum . The latter flexure mainly appears in mammals and sauropsids (reptiles and birds), whereas the other two, and principally the cephalic flexure, appear in all vertebrates (the sum of the cervical and cephalic ventral flexures is the cause of the 90-degree angle mentioned above in humans between body axis and brain axis). This more realistic concept of
150-597: 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
180-475: 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
210-408: 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
240-484: A person jumped directly up and then down, their body would be moving through the transverse plane in the coronal and sagittal planes. A longitudinal plane is any plane perpendicular to the transverse plane. The coronal plane and the sagittal plane are examples of longitudinal planes. Sometimes the orientation of certain planes needs to be distinguished, for instance in medical imaging techniques such as sonography , CT scans , MRI scans , or PET scans . There are
270-399: 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
300-473: A variety of different standardized coordinate systems. For the DICOM format, the one imagines a human in the anatomical position, and an X-Y-Z coordinate system with the x-axis going from front to back, the y-axis going from right to left, and the z-axis going from toe to head. The right-hand rule applies. In humans, reference may take origin from superficial anatomy , made to anatomical landmarks that are on
330-419: 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 ,
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#1732863107201360-473: Is a transverse plane passing through the pylorus . In discussing the neuroanatomy of animals, particularly rodents used in neuroscience research, a simplistic convention has been to name the sections of the brain according to the homologous human sections. Hence, what is technically a transverse (orthogonal) section with respect to the body length axis of a rat (dividing anterior from posterior) may often be referred to in rat neuroanatomical coordinates as
390-446: 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
420-560: Is derived from Latin articulatio . Humans have also developed lighter, more fragile joint bones over time due to the decrease in physical activity compared to thousands of years ago. Anatomical planes An anatomical plane is a hypothetical plane used to transect the body, in order to describe the location of structures or the direction of movements. In human and non-human anatomy, three principal planes are used: There could be any number of sagittal planes, but only one cardinal sagittal plane exists. The term cardinal refers to
450-459: 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
480-433: 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
510-416: The anteroposterior part of the brain to which the description refers (e.g., transverse to the midbrain, or horizontal to the diencephalon). A necessary note of caution is that modern embryologic orthodoxy indicates that the brain's true length axis finishes rostrally somewhere in the hypothalamus where basal and alar zones interconnect from left to right across the median line; therefore, the axis does not enter
540-436: 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
570-415: The body. However, the situation is more complex, since comparative embryology shows that the length axis of the neural tube (the primordium of the brain) has three internal bending points, namely two ventral bendings at the cervical and cephalic flexures (cervical flexure roughly between the medulla oblongata and the spinal cord , and cephalic flexure between the diencephalon and the midbrain ), and
600-483: The brain primordium, jointly with establishing what is ventral in the brain (close to the axial mesoderm) in contrast with what is dorsal (distant from the axial mesoderm). Apart from the lack of a causal argument for introducing the axis in the telencephalon, there is the obvious difficulty that there is a pair of telencephalic vesicles, so that a bifid axis is actually implied in these outdated versions. Some of these terms come from Latin. Sagittal means "like an arrow",
630-412: 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
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#1732863107201660-497: 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
690-410: 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
720-402: The longitudinal structure of vertebrate brains implies that any section plane, except the sagittal plane, will intersect variably different parts of the same brain as the section series proceeds across it (relativity of actual sections with regard to topological morphological status in the ideal unbent neural tube). Any precise description of a brain section plane therefore has to make reference to
750-610: 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
780-425: The one plane that divides the body into equal segments, with exactly one half of the body on either side of the cardinal plane. The term cardinal plane appears in some texts as the principal plane . The terms are interchangeable. In human anatomy, the anatomical planes are defined in reference to a body in the upright or standing orientation. The axes and sagittal plane are the same for bipeds and quadrupeds, but
810-440: The orientations of the coronal and transverse planes switch. The axes on particular pieces of equipment may or may not correspond to the axes of the body, especially since the body and the equipment may be in different relative orientations. When describing anatomical motion, these planes describe the axis along which an action is performed. So by moving through the transverse plane, movement travels from head to toe. For example, if
840-405: The skin or visible underneath. As with planes, lines and points are imaginary. Examples include: In addition, reference may be made to structures at specific levels of the spine (e.g. the 4th cervical vertebra , abbreviated "C4"), or the rib cage (e.g., the 5th intercostal space ). Occasionally, in medicine, abdominal organs may be described with reference to the trans-pyloric plane , which
870-410: The telencephalic area, although various authors, both recent and classic, have assumed a telencephalic end of the axis. The causal argument for this lies in the end of the axial mesoderm -mainly the notochord, but also the prechordal plate- under the hypothalamus. Early inductive effects of the axial mesoderm upon the overlying neural ectoderm is the mechanism that establishes the length dimension upon
900-450: 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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