PRACTICAL CONSIDERATIONS : THE FEMUR. 



361 



tubercle can be felt. The latter marks the line of union of the lower epiphysis 

 with the shaft. When the knee is flexed, the patellar surface, its borders, and part 

 of the articular surface of the condyles can be felt. 



PRACTICAL CONSIDERATIONS. 



Before the age of four the upper epiphysis is not distinct, and traumatism is apt 

 to result in separation of the upper cartilaginous end of the bone, — i.e., a fracture 

 through some part of the cartilaginous neck. Later three epiphyses may be affected 

 by injury, — viz., those for the head and the two trochanters. 



Fig. 377. 



/ 



/ 



/ 



/ 





Section through hip-joint, showing epiphyses of head and greater trochanter of femur. 



The epiphysis for the head is shaped like a hollow hemisphere set upon the 

 convex upper end of the neck. The epiphyseal line slopes downward and inward, 

 and is entirely within the synovial membrane. 



Separation by indirect violence occurs as a result of extreme extension of the 

 thigh, as in falls backward with the limb fixed, or as when a child carried in the 

 arms of a nurse throws itself violently backward. The force is thus in effect 

 applied at the lower end of the femur, which acts as the long arm of a lever. When 

 it is carried far backward the ilio-femoral ligament is put upon the stretch, and its 

 point of insertion becomes the fulcrum. The resistance (or weight) is at the point 

 where the forward movement of the short arm of the lever — the neck and head — 



