Joints

Joints Overview

  • Definition: Articulation where two or more bones meet.

  • Functions: Mobility and stability of the skeleton.

Structural Classifications of Joints

  • Fibrous: United by fibers (no joint cavity) - Example: sutures.

  • Cartilaginous: United by cartilage (no joint cavity) - Example: pubic symphysis.

  • Synovial: Have a synovial cavity (freely mobile) - Example: hip joint.

Functional Classifications of Joints

  • Synarthroses: Immovable - Example: fibrous sutures.

  • Amphiarthroses: Slightly movable - Example: intervertebral joints.

  • Diarthroses: Freely movable - Example: shoulder joint.

Synovial Joint Structure

  • Articular cartilage: Thin layer on ends of articulating bones.

  • Joint capsule: Composed of outer fibrous layer and inner synovial membrane.

  • Synovial fluid: Lubricates joint.

  • Ligaments: Reinforce joint capsule.

  • Menisci: Shock absorbers made of fibrocartilage.

  • Bursae: Cushioning fluid-filled sacs.

Types of Synovial Joints

  1. Ball-and-Socket: Hip, shoulder (movement in all planes).

  2. Condyloid: Wrist (movement in different planes).

  3. Gliding: Intercarpal joints (sliding motion).

  4. Hinge: Elbow, knee (flexion and extension).

  5. Pivot: Between radius and ulna (rotation).

  6. Saddle: Thumb joint (variety of movements).

Knee Joint Details

  • Largest joint: Comprised of femoropatellar and tibiofemoral joints.

  • Menisci: Medial and lateral; improve joint fit.

  • Ligaments: Include ACL, PCL, medial and lateral collateral ligaments for stability and movement prevention.

Common Arthritis Types

  • Rheumatoid Arthritis: Inflammation, joint destruction, treated with anti-inflammatories and surgery.

  • Osteoarthritis: Age-related, common in knees and hips, treated with lifestyle changes and pain relievers.

  • Gouty Arthritis: Uric acid crystals in joints, treated with diet changes and hydration.

Joint Injuries

  • Dislocations and Subluxations: Bones out of alignment; subluxation is a partial dislocation.

  • Bursitis: Inflammation of bursa, treated with rest and anti-inflammatories.

  • Torn Cartilage: Results from injury, may require arthroscopic surgery for repair.

  • Sprains and Strains: Ligament and muscle injuries, may require different treatments based on severity.