USMLE

Bone Structure

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Musculoskeletal
  1. Osteoblasts
  2. Osteoclasts
  3. Osteocytes
  4. Spongy Bone
  5. Compact Bone
  6. Bone Structure
  7. Cartilage
  8. Joints
  9. Type 1 vs. Type 2 Muscle Fibers

Summary

Bone structure consists of three components. The first is the epiphysis, which describes the rounded ends of the bone. The epiphysis is entirely covered by cartilage, and is the location where bones form joints with one another. The second structural feature is the hollow middle between the two epiphyses, known as the diaphysis. The diaphysis is filled with bone marrow. Finally, between the epiphysis and the diaphysis, there is the metaphysis. The metaphysis includes the growth plate, which is the location where bones grow in length during childhood.

Key Points

  • Bone Structure
    • Bones vary but share general structural features
      • Epiphysis 
        • Rounded ends
        • Forms joint surfaces
          • Covered by cartilage
      • Diaphysis 
        • Hollow central shaft
          • Filled with bone marrow
      • Metaphysis 
        • Regions where diaphysis and epiphysis meet
        • Contains growth (epiphyseal) plate