Classification of Joints
Composition of a bone.
The hard outer part of the bone.
The shaft of the bone.
The head of the bone.
The harder tissue of the bone near the periosteum.
The softer tissue of the bone near the centre.
The larger the haversian canals (blood vessels) in a bone, the less dense and more spongy it is.
Joints are classified in the following way:
- Fused (fixed), such as the cranium
- Cartilageinous (slightly moveable), such as the cranium
- Synovial (free)
Synovial joints all have synovial cavities, within which fluid is contained to aid movement.
They are categorised as: Gliding, Hinge, Pivot, Saddle and Ball & Socket.
Gliding: Exhibit slight movement in two planes, such as between the carpals.
Hinge: Exhibit movement in one plane and are more stable, such as the elbow and the phalanges.
Pivot: Exhibit movement around one axis, such as the first two cervical vertebrae, and the radius.
Saddle: Exhibit movement around two axes, such as the wrist.
Ball and Socket: Exhibit movement in all planes and are therefore less stable, such as the hip and the shoulder.
Fig.6 Ball and Socket joint.