osteometry; the measurement of the bones 



95 



of the joint. If, now, the axis of the shaft be drawn, EF, intersecting 

 the line CD at E, the angle formed, CEF, is that between the joint axis 

 and that of the ulna, or of the forearm, the joint axis angle. 



10. Lateral divergence angle. — This angle, which is that made between 

 ulna and humerus during extension, might equally well be placed under 

 either bone, since it involves both to an equal degree ' Under the more 

 common name of the "Elbow angle" its more extreme case, in which the 

 two parts, upper and lower arm are set obliquely to each other in the 

 living, this angle has been frequently noted and extensively commented 

 upon. The true relation of these two parts is naturally a matter of the 

 bones concerned, and is due to the two angles, cubital (Humerus III, 2) 



Fig. 35. — Lateral divergence angle of elbow joint. {After Fisher.) 



I South German (Baden) 

 II Negro 

 III Australian 

 IV Australian 



and joint-axis (Ulna, 9), which may vary quite independently of each 

 other The four possibilities are presented in Fig. 35, taken from Fischer. 

 In the first case both cubital and joint axis angle are considerably less 

 than 90°, i.e., the axes are both obliquely set, the result being a pro- 

 nounced divergence of the forearm from the line of the humerus; in 

 II, where the cubital angle is oblique, and the joint axis nearly straight 

 (the angle even more than 90°), and in II, where the reverse is true, and 

 the cubital angle is straight (88°), there is a moderate amount of lateral 

 divergence. In IV each angle is practically a right angle, one compen- 

 sating exactly with the other, (88° and 92°), and the result is a perfectly 



