Lecture on Skeletal System and Joints

Introduction

• Skeletal system more than just bones
• Involves cartilage, fibrous connective tissue, and joints
• Joints: have more joints than bones, essential for movement

Skeletal System Structure

Divisions

• Axial Skeleton

  • 80 bones: skull, vertebral column, thoracic cage
  • Skull: 8 cranial, 14 facial bones
  • Vertebral Column: 33 irregular bones
    • Starts with atlas vertebra
    • Protects spinal cord
  • Thoracic Cage: 12 pairs of ribs, sternum
    • Protects vital organs

• Appendicular Skeleton

  • Upper and lower limbs, pectoral and pelvic girdles
  • Similar structure in limbs: one bone, two bones, lots of bones, digits

Physiology of the Skeletal System

Joints

• Types of Joints

  • Synarthroses: non-moving joints (e.g., skull joints)
  • Amphiarthroses: partly moving joints (e.g., pubic bones)
  • Diarthroses: fully movable joints (e.g., knees, elbows)

• Structural Classifications

  • Fibrous Joints: dense connective tissue, mostly immovable
  • Cartilaginous Joints: united by cartilage, low movement
  • Synovial Joints: fluid-filled cavity, freely movable
    • Contains synovial fluid, reduces friction

Movements

• Gliding Movements: Plane joints, e.g., wrist

• Angular Movements:

  • Flexion: Decreasing angle between bones
  • Extension: Increasing angle
  • Hyperextension: Beyond normal range
  • Abduction: Moving away from body
  • Adduction: Moving toward body
  • Circumduction: Circular movement

• Rotational Movements

  • Ball and socket joints (e.g., shoulder, hip)
  • Rotation around axis

• Special Movements

  • Opposition: Thumb touching fingertips
  • Supination/Pronation: Rotating forearm

Conclusion

• Overview of skeletal structure and joint classification
• Special thanks to contributors and patrons of educational content