Joints can be simply defined as articulations of bones, which functions by providing shape to the skeleton system, protects bones by holding them together securely and also helps in movement. Based on structure and functions, joints have been further classified into different types.
A synovial joint is one among the three types of joints, which are classified based on structure and is the most common type of joint in the human body.
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Let’s learn more in detail about Synovial Joints
What are Synovial Joints?
A joint, which is merged or combined with bones and is departed by a fluid present within the joint cavity are called synovial joints. They are freely movable and the most common type of joints. All limb joints and other joints are examples of synovial joints. Similar to other joints, synovial joints are directly connected to each other with fibrous connective tissue or cartilage and they help bones to move smoothly by providing increased joint mobility.
Structural Features of Synovial Joints
Synovial joints are described by the presence of a joint cavity and their walls are formed by articular capsules. These joints are more complex than other types of joints and their structural components include: :
- Synovial fluid
- Articular capsule
- Articular cartilage
- Reinforcing ligaments
- Joint cavity or capsules
Types of Synovial Joints
These joints are diarthrosis joints and almost all the joints present in our body are synovial joints. There are six different types of synovial joints and are mainly classified based on their shapes of the articulating surfaces of bones that form each joint.
- Plane joints
These joints have essentially flat articular surfaces and are involved in slipping or gliding movements. Plane joints are present between carpals of wrist and in ankle joints that produce different types of movements such as:
- Nonaxial movement
- Hinge joints
A type of a joint with cylindrical projections, which hardly resembles the hinge of a door. They are uniaxial joints with a single plane motion that permit flexion and extension only. A hinge joint is present in the elbow and between interphalangeal joints.
- Pivot joints
These joints comprise a cylindrical surface, which rotates within a ring of other bones. They are uniaxial joints with a single plane motion. A pivot joint is present between the axis and the proximal radioulnar joint.
- Condyloid or Condylar or Ellipsoidal joints
A joint with an oval articular surface in which one bone fits into a complementary depression into another. They are biaxial joints with biaxial movement, which permit movements in all angular motions. i.e back and front, side to side. These joints are present between wrist joints, knuckle joints, metacarpals and phalanges joints.
- Saddle joints
It is a joint with a convex or concave surface. They provide a biaxial movement and are quite similar to condyloid joints. These joints are present between the carpometacarpal joint of the thumb.
- Ball-and-socket joints
A joint with a hemispherical or spherical head in which a bone forms a joint with a cuplike socket of another. They provide multiaxial joints and are most freely moving synovial joints with the widest range of motion. They are present between shoulder and hip joints.
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This article concludes with an introduction to synovial joints, their types, structure and functions. To know more about joints, types of joints, other related topics and important questions, keep visiting our website at BYJU’S Biology.