178 JOHN C. KOCH 



Part III 



The mathoniatical analysis of the femur 215 



lutrodiution. 1. The Cuhnann model. 2. Mathematical objections to 



Culmann's conclusions 215 



The basis of a mathematical analysis of the femur 217 



The mechanism of human locomotion 218 



Materal studied '. 221 



The foniur as a structure. 1. General. 2. External loads. (A) The ef- 

 fect of muscle action. (B) The effect of body weight. 3. Magnitude 

 and direction of the external load. 4. Assumed load on the femur. 5. 



Force diagram 222 



Analysis of the mechanical properties of the femur. 1. Analysis of serial 

 transverse sections. 2. Center of gravity. 3. Neutral axis and neu- 

 tral surface. 4. Moment of inertia. 5. Analysis of sections. 6. Bend- 

 ing strength. 7. Torsional strength 227 



Effects of external load. 1. Shearing and axial loads. 2. Resolution of 

 load. (A) Axial load and vertical shear. 3. Bending moment. 4. 

 Vertical and horizontal shear. 5. The unit-stresses due to external 

 load. (A) Axial unit-stresses. (B) Unit-Stresses due to bending mo- 

 ment. (C) Horizontal and vertical shearing unit-stresses. 6. Maxi- 

 mum unit-stresses in the femur. 7. The lines of maximum internal 

 stress 234 



Part IV 



The normal inner architecture of the femur 249 



The inner architecture of the upper femur. 1. Frontal longitudinal sec- 

 tions; (A) The medial (compressive) system of Trabeculae. The (a) 

 Secondary compressive group, (b) Principal compressive group. (B) 

 The lateral (tensile) system of Trabeculae. (c) The greater trochanter 

 group, (d) The principal tensile group, (e) The secondary tensile 

 group. (C) General. 2. The inner architecture of the sagittal mid- 

 section. (A) Structural features. 3. The serial transverse sections 



of the upper femur 251 



The shaft of the femur. 1. Frontal longitudinal sections. 2. Sagittal 



longitudinal sections. 3. Serial transverse sections 259 



The distal portion of the femur. 1. Frontal section. 2. Sagittal sec- 

 tion. 3. Serial transverse sections. 4. Structural features 261 



Part V 



Significance of the inner architecture of the femur 265 



General 265 



Significance of the inner architecture of the upper femur. 1. Frontal 



sections 266 



Further significance of the spongy structure of the upper femur 267 



Conclusions 268 



Significance of the inner architecture of the shaft. 1. Economy for re- 

 sisting shear. 2. Economy for resisting bending moment. 3. Economy 

 for resisting axial stress. 4. Conclusions 268 



