joints

Joints and Their Classification

  • Expectations & Overview

    • Joints: Points where two bones meet, some are movable.
    • Arthrology: Study of joint structure, function, dysfunction.
    • Kinesiology: Study of musculoskeletal movement.
    • Classification: Joints categorized into bony, fibrous, cartilaginous, synovial.

  • Types of Joints

    • Bony Joints (Synostosis): Immobile joints formed by the ossification of the gap between bones (e.g., cranial bones in infants).
    • Fibrous Joints (Synarthrosis): Bones connected by collagen fibers.
    • Types:
      • Sutures: Immobile or slightly mobile joints in skull.
      • Gomphoses: Joint between teeth and sockets.
      • Syndesmoses: Bones linked by long collagen fibers, allowing more mobility.
    • Cartilaginous Joints (Amphiarthrosis): Bones linked by cartilage.
    • Types:
      • Synchondroses: Bones joined by hyaline cartilage (e.g., rib to sternum).
      • Symphyses: Bones joined by fibrocartilage (e.g., pubic symphysis).
    • Synovial Joints (Diarthrosis): Freely movable joints separated by a joint cavity.

  • Synovial Joint Anatomy

    • Articular cartilage, joint cavity with synovial fluid, and joint capsule.
    • Accessories: Ligaments, tendons, and bursa enhance joint function.

  • Movement Mechanics

    • Leverage systems: Long bones act as levers around fulcrums (joints).
    • Mechanical Advantage (MA): Ratio of output force to input force; helps understand joint movement efficiency.
    • Types of levers: First, second, and third-class levers with varying arrangements of fulcrum, effort, and resistance.

  • Range of Motion (ROM): Determined by structure of articular surfaces and surrounding tissues, varying by joint type

  • Joint Classes of Synovial Joints:

    • Six types defined by movement and structure: ball-and-socket, condylar, saddle, plane, hinge, pivot.

  • Movement Terminology:

    • Opposing pairs for articulation (e.g., flexion/extension, abduction/adduction).
    • Special hand movements: opposition (thumb to finger), radial/ulnar flexion.

  • Joint Dysfunction: Common issues include arthritis, joint injuries, and joint replacements (arthroplasty).