400 On the Augle of the Elbow 



deflection (that is, the difference between that at flexion and that at 

 extension) is divided by the number of degrees of motion of the elbow. 

 The deflection being greatest in the negro male, the result becomes 

 still greater because the motion of his elbow is the smallest. This quotient 

 becomes the degree of lateral deflection for one degree of elbow motion. 

 If this in turn is multiplied by 180, the amount of deflection is obtained, 

 \n case the elbow joint could be moved from zero to 180 degrees. This 

 quotient I shall spealc of as the total deflection, it being the amount of 

 deflection in case the elbow joint had a motion of 180 degrees. For ex- 

 ample, in the right arm of subject No. 925 the deflection is between 

 — 4.5 degrees and 1 degree or 5.5 degrees. This divided by the number 

 of degrees of motion (169 — 50) 119 makes .0462 or the number of 

 degrees of lateral deflection of the forearm for each degree of flexion or 

 extension. In turn this multiplied by 180 gives the total deflection 

 could the forearm move through an entire semicircle. In this case it 

 amounts to (.0462 X 180) 8.3 degrees. Now it is found that the deflec- 

 tion per degree varies for different positions of the forearm, as is shown 

 in the following table. In the first column the deflection per degree is 



Degree of deflection for each degree of motion from 

 Race sex A rm ^^-i-^™ a""°" '"° '" ''""'""" ''"TJf^^fvi^^^f/r " 



iRigbit 08 

 Left 07 

 Both 075 



[ Right 07 



Female \ Left 075 



{ Both 07 



Both 075 



C f Right 04 



Male \ Left 025 



( Both 0.3 



r Right 11 



Female \ Left 10 



( Both 105 



Both 05 



Average 07 .085 .08 



given between maximum flexion and 90 degrees, in the second from 90 

 degrees to maximum extension, and in the third the average degree of 

 deflection for the whole motion of the forearm. Of course to determiue 

 each figure it was necessary to start with an average. It is seen from 

 the faille that the lateral deflection per degree of motion is generally less 

 when the elbow is flexed less than a right angle than when it is extended 

 beyond it. The deflections seems to increase as the maximum extension 

 is approached. This is to be accounted for in part by the irregularity of 



Negro 



European 



