THE LAWS OF BONE ARCHITECTURE 



JOHN C. KOCH 



From the Department of Anatomy, Johns Hopkins Medical Schoot, Baltimore, Md. 



TWENTY-EIGHT FIGURES AND FIVE PLATES 



CONTENTS 



Part 1 



Introduction 17" 



Acknowledgments 180 



Object of paper 181 



Historical, brief review of the literature )-81 



Part II 



Summary of mathematical principles 186 



Introduction 186 



Definitions. 1. Mechanics. 2. Statics. 3. Graphic statics. 4. Force. 



5. Effects of force. 6. Stress. 7. Deformation. 8. Unit-stress. 9. 

 Compression. 10. Tension. 11. Shear, torsion. 12. Elasticity. 13. 

 Elastic limit. 14. Ultimate strength. 15. Modulus of elasticity 187 



Composition and resolution of forces. 16. Resultant. 17. Components. 

 18, 19, 20. Levers and moments. 21. Couple 192 



Theory of beams. 22, 23. Reactions. 24, 25. Vertical shear. 26, 27. 

 Beams. 28-32. Relation between internal stresses and external loads. 

 33-37. Laws of internal stress. 34. Resisting moment. 35. Resisting 

 shear. 36. Laws of beams. 37. Neutral surface and neutral axis. 38- 

 40. Moment of inertia. 41. Section modulus. 42. Summary, moment 

 of inertia 193 



Theory of column action. 43-45. Factors affecting strength. 46, 47. 

 Determination of moment of inertia. 48. Example. 49. Columns 200 



Horizontal shear in beams. 50. Effect of horizontal shear in beams. 51. 

 Computation of horizontal shearing stresses, example. 52. Vertical 

 shearing stresses. 53. Lines of stress in beams 204 



Properties of bone. 1. Specific gravity. 2. Tensile strength. 3. Com- 

 pressive strength. 4. Shearing strength. 5. Modulus of elasticity. 



6. Torsional strength. 7. Comparison of bone with other materials. 



8. Table of strengths of materials 211 



177 



THE AMERICAN JODRNAb OF ANATOMY, VOL. 21, NO. 2 

 MARCH. 1917 



