254 



JOHN C. KOCH 



1). Tlic principul ('()m])ressive group. This group of trabec- 

 ulae (figs. 21 tiiid 28) springs from the medial portion of the 

 shaft just above the group above-described, and spreads up- 

 ward and in shghtly radial smooth curved lines to reach the 

 upper portion of the articular surface of the head of the femur. 

 These trabeculae are placed very closely together and are the 

 thickest ones seen in the upper femur. They are a prolonga- 

 tion of the shaft, from which they spring in straight lines which 

 gradually curve to meet at right angles the articular surface. 



Fig. 22 Diagram of curves of different radii, intersecting at right angles. 

 Detailed discussion of this figure is given in Part IV, under 'The Secondary 

 Compressive Group.' (P. 253.) 



There is no change as they cross the epiphyseal line. They 

 also intersect at right angles the system of lines which rise from 

 the lateral side of the femur. There are a few light trabeculae 

 of this group which rise along the lower portion of the neck of 

 the femur and end below the fossa of the ligamentum teres. 



This system of principal and secondary compressive trabeculae 

 corresponds in position and in curvature with the lines of maxi- 

 mum compressive stress, which were traced out in the mathe- 

 matical analysis of this portion of the femur (fig. 19). 



