Types of joints of the human body

The 206 bones of the human body provide structural scaffolding, provide protection to internal organs, and facilitate body movements (locomotion). However, for this to be possible, it is important that the bones can articulate with each other. Next we will show you the types of joints that exist in the human body , which can be defined as the point where two bones are next to each other (with or without the ability to move). These have been classified according to the range of motion they exhibit and the type of tissue that holds neighboring bones together.

Joints

DefinitionJoints can be defined as the point where two bones meet next to each other (with or without the ability to move). These have been classified according to the range of motion they exhibit and the type of tissue that holds neighboring bones together.
According to the fabric
  • Synovial joints
    • Ball joints or ball and socket joints
    • Flat joints or arthrodias
    • Hinge or trochlear joint
    • Pivot or trochoid joints
    • Condyloid or ellipsoidal joints
    • Saddle or sellar joints
  • Fibrous joints
    • Sindesmosis
    • Gonfosis
    • Sutures
  • Cartilaginous joints
According to the movement
  • Uniaxial
  • Biaxial
  • Poliaxial
  • ovement sliding

Types of joints

Synovial joints

Synovial joints are those that move freely since the surfaces do not have direct contact with each other. Range of motion is defined (that is, limited) by the joint capsule, the supporting ligaments, and the muscles that cross the joint. Most joints in the upper and lower extremities are synovial.

Most synovial joints are lined with hyaline cartilage , except for the temporomandibular joint, which is lined with fibrous cartilage . The joint is wrapped in a capsule that lines the joint cavity. The interior of the capsule is covered by a synovial membrane that is responsible for producing and secreting the synovial fluid that lubricates the joint, which helps reduce friction between the ends of the bones when they articulate with each other.

Ligaments, tendons, and skeletal muscle provide additional capsule reinforcement. These joints are capable of a wide variety of movements and are consequently the most susceptible to dislocation . There are several examples of synovial joints, all of which are capable of an eclectic arrangement of movements. These include:

  • externalclavicular
  • shoulder
  • elbow
  • hips
  • knee
  • radiocarpian
  • proximal tibiofibular joints

Fibrous joints

Unlike synovial joints, fibrous joints are much simpler and less mobile . The articular borders of the bones are joined by fibrous connective tissue . Movement in these joints is negligible. Fibrous joints are found in only three areas of the body.

In the skull , by three years of age, all the fontanelles (soft regions between the skull bones) would have fused together. The remnants, called cranial sutures, are fibrous connections (suture ligaments) that occupy the joint space. The adjacent bones will ossify completely over time, which can result in obliteration of the suture lines.

A second example of fibrous joints is the distal tibiofibular and cuboideonavicular joints (cuboid and navicular bones). They are held in place by interosseous ligaments and are called syndesmosis joints (translated from the Greek to mean “joined with a band”).

The final fibrous joint is in the mouth , where the pinned end of the teeth articulates with the dental sockets. This joint is known as a gomphosis joint .

Cartilaginous joints

Cartilaginous joints are mainly characterized by the fact that they connect with neighboring bones through cartilage . They exhibit a range of motion that is located between the synovial and fibrous joints. There are two types of cartilaginous joints, synchondrosis and symphysis joints .

Synchondrosis joints (translated from the Greek meaning “with cartilage”), also called primary cartilage joints , are joints in which hyaline cartilage meets bone. These highly immobile joints can be seen in the costochondral joints of the anterior thoracic cavity and in the epiphyseal plates of the long bones.

The symphysis ( secondary cartilaginous ) joints are the second group of cartilaginous joints. They are found mainly along the midline of the body. Characteristics of the joint include adjacent bony surfaces lined with hyaline cartilage and connected by fibrous tissue with some degree of mobility. The intervertebral joints, the pubic symphysis, and the manubriosternal angle of Louis are examples of symphysis joints. In some cases there may be joint cavities, but they are never synovial in nature.

According to the ranges of motion

There are four general classifications of joint movements. Depending on their location, the joints can:

  • move back and forth along a single axis (uniaxial)
  • move on two different axes (biaxial)
  • move through the three axes (polyaxial)
  • gliding over each other (gliding movements), in the case of flat bones

The uniaxial and biaxial joints can be further subdivided in relation to the movements of particular joints. For example, elbows and knees are classified as hinge joints; flexion and extension can only occur in these joints.

Radius ulnar joints are known as pivot joints – the radius rotates around the ulna at the point of contact. While the temporomandibular joints are examples of condylar joints, the condyle of the mandible is located in the mandibular fossa of the temporal bone and movement is restricted to one plane.

Biaxial joints are ellipsoidal . The ellipsoidal joint in the wrist allows independent ulnar or radial deviation, as well as flexion or extension of the hand.

A combination of these movements gives the false impression that the wrist joint is polyaxial. The first carpometacarpal joint is shaped like an inverted saddle that allows movement in two axes, although not independently. These movements are vital for the opposition of the thumb and, subsequently, the functionality of the hand.

The most mobile of all the joint classifications, the polyaxial joints , are seen in the shoulder, hip, and sternoclavicular joints. They are also called “ball and socket” joints because of the spherical shape of one articular surface (the head of the humerus) and the shape of the socket on the other surface (the glenoid socket). The limbs joined by these joints are capable of adduction, abduction, extension, and flexion. The movements of the sternoclavicular joint differ in a way that it suffers a prolongation, retraction, elevation and depression.

Finally, gliding joints (or flat joints) can be found in the acromioclavicular, intermetacarpal, proximal tibiofibular joints, and in some of the intertarsal joints.

Clinical aspects

Osteoarthritis

Highly mobile joints are the most susceptible to injury. One of the most common forms of joint-related pathology is osteoarthritis (OA). Although the nomenclature implies an inflammatory process, this degenerative joint disease (DED) is most often of idiopathic etiology and affects older people. It is most often described as the gradual deterioration of the cartilaginous surface of the joint . Repeated trauma to the joints or birth defects can also predispose younger people to OA.

Rheumatoid arthritis

The aforementioned inflammatory variant of synovitis is rheumatoid arthritis (RA). Also of unknown origin, this DJD also results in the obliteration of the articular cartilage of the joint with the consequent distortion and stiffness of the joint . Although the joints are predominantly affected by RA, the cardiovascular, respiratory, and integumentary systems can also be susceptible to damage from the inflammatory process.

Drop

The inability to effectively break down or excrete uric acid can result in accumulation and crystalline deposition of the metabolite in the joints. This gouty arthritis is commonly caused by deficient or defective hypoxanthine guanine phosphoribosyl transferase (HGPRT), an enzyme that facilitates the conversion of uric acid to useful purine bases. The accumulation of gout crystals in the joint cavities will reduce the joint’s range of motion and can lead to damage to the cartilaginous lining.

Sprains and dislocations

Sprains and dislocations are also common injuries that occur in the joints. Hyperextension or rupture of one of the ligaments, muscles, or tendons that support the joint will cause a sprain. However, the joint may not necessarily be displaced. If enough force is transmitted to the joint during trauma, adjacent bones can dislocate (dislocate) . The shoulder is the most common dislocated joint. It can move forward, backward, and more often downward (superior dislocation is less likely due to reinforcement of the deltoid muscle). Hip, elbow, knee, ankle, and digital dislocations are also common.

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