THE PRINCIPLES OF MYODYNAMICS. Il5 



35o pounds, and die pressure on the joint- 

 surfaces equals 400 pounds. It may be re- 

 marked, that the tendency of the weight is put 

 on the joint surfaces by means of the articular 

 ligaments, and is thus added to the retentive 

 action of the quadriceps : — The static work of 

 the bone is greater than the kinetic work of the 

 muscle. 



108. See Fig. 2 5 : The description is the 

 same as before — except that the tibia and the 

 femur meet at a right angle. The condyles of 

 the femur meet the base of the tibia further back 

 than in the previous instance. The distance 

 P D is somewhat more than two inches — but let 

 us say two inches. The distance D C is about 

 four inches. The component triangle is P D C. 

 The rectangular components are to each other 

 as 2:4, and, since the weight is fifty pounds, 

 the component D C equals 360 pounds, and the 

 component PD equals 176 pounds. These 

 two components will be resolved from the force 

 of the quadriceps — which will equal 391 pounds. 

 But D C is a retentive as well as a moving com- 

 ponent ; while P D is a displacing component, 



