Lecture on Types of Synovial Joints

Introduction

• Synovial joints categorized by:
  • Shape of articular surface
  • Type of movement
• Six types of synovial joints

Types of Synovial Joints

1. Plane Joint

• Characteristics:
  • Non-axial movement (slipping motion)
  • Flat articular surfaces
• Examples:
  • Carpals, tarsals
  • Articular surfaces of vertebrae
• Movement:
  • Sliding/gliding movements

2. Hinge Joint

• Characteristics:
  • Uniaxial movement (one plane, sagittal plane)
  • Cylinder fits into a trough
• Examples:
  • Elbow joint (trochlea of humerus and trochlear notch of ulna)
  • Interphalangeal joints (between fingers)
• Movement:
  • Flexion and extension

3. Pivot Joint

• Characteristics:
  • Uniaxial rotation
  • Bone or ligament sleeve surrounds an axle
• Examples:
  • Proximal radioulnar joint (radius rotates around ulna)
  • Atlantoaxial joint (Atlas and Axis)
• Movement:
  • Rotational movement (supination and pronation of the forearm)

4. Condylar Joint

• Characteristics:
  • Biaxial movement
  • Oval articular surface (concave and convex surfaces)
• Examples:
  • Metacarpophalangeal joints (knuckles)
  • Wrist joint
• Movement:
  • Multiple directions, stable

5. Saddle Joint

• Characteristics:
  • Biaxial movement
  • Convex and concave surfaces interlocking
• Examples:
  • Carpometacarpal joint of the thumb
• Movement:
  • Abduction, adduction, flexion, and extension

6. Ball and Socket Joint

• Characteristics:
  • Multiaxial movement
  • Ball fits into a socket
• Examples:
  • Shoulder joint (glenohumeral joint)
  • Hip joint
• Movement:
  • Circumduction, rotation, abduction, adduction, flexion, extension
• Stability vs. Mobility:
  • High mobility means lower stability
  • Shoulder joint is commonly dislocated due to high mobility

Conclusion

• The trade-off between joint mobility and stability
• Highly mobile joints, like the shoulder, are less stable and more prone to dislocation