1. Joint Classifications, Characteristics & Types

2. Joint: a point of connection between two bones
Strands of connective tissue and ligaments hold the bones together and ensure the stability of joints

3. Joint Classification
Joints are classified according to their motion capabilities:
Synarthroses
Immovable
Amphiarthroses
Slightly movable
Diarthroses
Allow the greatest amount of motion

4. Joint Classification Cont’d
Joints are further classified by the material that joins them:
Fibrous joint
Allow no movement
e.g. sutures of the skull
Cartilaginous joints
Allow limited movement
e.g. intervertebral discs
Synovial joints
Allow large range of movements
e.g. hip joint

5. Characteristics of Synovial Joints
Hyaline cartilage
A protective layer of dense white connective tissue that covers the ends of the articulating bones
Joint cavity
Synovial membrane
Covers joint cavity, except over the surfaces of the articular cartilages
Secretes the lubrication fluid
Synovial fluid
Lubricates the joint
Capsule (concave articulating surface)
May or may not have thickenings called intrinsic ligaments
Extrinsic ligaments
Support the joint and connect the articulating bones of the joint

6. Types of Synovial Joints
There are three basic types of synovial joints:
Uniaxial (rotation only about one axis)
Biaxial (movement about two perpendicular axes)
Multiaxial (movement about all three perpendicular axes)

7. Types of Synovial Joints Cont’d
Synovial are further classified into:
1. Hinge Joint
2. Pivot Joint
3. Condyloid Joint
4. Saddle-shaped joint
5. Ball and Socket Joint
6. Plane Joint

8. Hinge Joint
Uniaxial
Has one articulating surface that is convex, and another that is concave
e.g. humero-ulnar joint,
interphalangeal joint

9. Pivot Joint Uniaxial Permits rotation e.g. radioulnar joint
atlantoaxial joint

10. 3. Condyloid (Knuckle) Joint
Biaxial (flexion-extension, abduction-adduction, circumduction)
The joint surfaces are usually oval
One joint surface is an ovular convex shape, and the other is a reciprocally shaped concave surface
e.g. metacarpophalangeal joints
carpals joints
radiocarpal joints

11. 4. Saddle Joint
Biaxial (flexion-extension, abduction-adduction, circumduction)
The bones sit together as in sitting on a horse
e.g. carpometacarpal joint of the thumb

12. 5. Ball and Socket Joint Multiaxial (rotation in all planes)
A rounded bone is fitted into a cup like receptacle
e.g. shoulder and hip joints

13. 6. Plane (Gliding) Joint Uniaxial (permits gliding movements)
The bone surfaces involved are nearly flat
e.g. intercarpal, intervertebral and acromioclavicular
joints