Joints
Joints occurs where bones meet. They not only hold our skeleton together, but also gives it the mobility. Joints have three categories.
- Immovable joints
- Slightly movable joints
- Freely movable joints
Freely movable joints also have three types.
- Hinge joints
- Ball and socket joint
- Fibrous Joints:
These joint are held together by short fibers embedded in connective tissues. Such joints are present in the skull, and they fix teeth into the jaws.
- Cartilaginous Joints:
These joints allow little or no movement . Hyaline cartilage forms joint between growing bone. The bones held together by fibrous cartilage are found between vertebrae at the point where coxal bones meet in front of the pelvis.
- Synovial Joints:
These joints contain a cavity filled with fluid and are adapted to reduce friction between the moving joints. The joint is surrounded by a layer of connective tissues called "Fibrous Capsule" and their inner layer the synovial membrane. Some parts of capsule may be modified to form distinct Ligament, holding the bones together.
Based on the structure and movement allowed, the synovial joints can be classified further into major categories.
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| Synovial joints |
- Hinge Joint:
The joint that allows the movement in two directions. These are at elbow and knee. At these joints, pair of muscles are arranged in the same plane as that of joints. One end of each muscle, the origin is fixed to the immovable bone on one side of the joint and the other end of muscles, the the insertion is attached to the far side of the joint.
- Ball & Socket joints:
The joint that allows the movement in several directions. Such joints have at least two pairs of muscles present perpendicular to each other. They provide maximum flexibility. Hip joint and shoulder joint are the examples of ball & socket joints.
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