138 THE PRINCIPLES OF MYODYXAMICS. 



facts have important bearings in the treatment 

 of hip-joint disease and fracture of the femoral 

 neck. 



135. If the weight acts on the lower end of 

 the femur in the direction of b w — w b d being 

 a right angle — then the entire weight will resist 

 the moving component of the muscle : And 

 the greater the weight, the greater the moving 

 component of the muscle ; but the greater the 

 moving component of the muscle, the greater 

 the retentive component of the muscle : Hence 

 the greater the weight, the greater the pressure 

 of the head of the femur on the surface of the 

 acetabulum. 



138. If the weight act on the lower end of 

 the femur in any direction s w beyond the per- 

 pendicular w b, the rectangular components will 

 be s b and b w : s b will be a retentive compon- 

 ent, augmenting the action of the retentive 

 component of the muscle, while b w will be a 

 resisting component, antagonizing the moving- 

 component of the muscle : And the nearer the 

 weight acts at right angles to the femoral shaft, 

 the greater will be the retentive components. 



