Types and Features of Human Bones

Sep 29, 2024

Lecture Notes: Types of Bones and Structural Features

Overview of the Skeletal System

  • Total Bones: 206
  • Divisions:
    • Axial Skeleton (80 bones):
      • Includes skull, ear bones, throat bones, hyoid, ribs, sternum, vertebra
    • Appendicular Skeleton (126 bones):
      • Bones of upper and lower limbs, girdles connecting to axial skeleton

Types of Bones

  1. Long Bones
    • Typical long bones, e.g., femur
  2. Short Bones
    • Cube-shaped, e.g., carpal bones
  3. Flat Bones
    • Thin and broad, e.g., sternum
  4. Irregular Bones
    • Complex shapes, e.g., vertebrae
  5. Sesamoid Bones
    • Embedded in tendons, e.g., patella
  6. Sutural Bones
    • Extra bones between cranial bones; vary among individuals

Special Note on Sutural Bones

  • Found in cranial sutures
  • Fontanelles in infants allow cranial bone flexibility during birth

Structural Features of Bones

  • Markings:
    • Projections (Processes): For ligament and tendon attachment
    • Depressions/Openings: For soft tissue passage and joint formation

Types of Bone Markings

  1. Fissure: Narrow slit for blood vessels or nerves (e.g., superior orbital fissure)
  2. Foramen: Large holes (e.g., foramen magnum)
  3. Fossa: Shallow depressions (e.g., mandibular fossa)
  4. Sulcus: Small groove, not a full opening
  5. Meatus: Tube-like opening (e.g., external auditory meatus)
  6. Condyle: Rounded projection; articular surface (e.g., condylar process)
  7. Facet: Flat articular surface (e.g., vertebra facets)
  8. Crest: Prominent ridge (e.g., medial sacral crest)
  9. Epicondyle: Rough projection above a condyle
  10. Line: Less prominent ridge
  11. Spinous Process: Narrow projection from a vertebra
  12. Trochanter: Large bumpy projection on the femur
  13. Tubercle: Small rounded projection
  14. Tuberosity: Roughened surface for attachment

Important Connections

  • Ligaments: Connect bone to bone
  • Tendons: Connect muscle to bone

These features and types of bones are crucial for understanding bone function and structure within the human skeletal system. Each type and feature has specific roles, from providing structural support to facilitating movement and protecting vital organs.