236 SURGICAL APPLIED ANATOMY. [Chap. xin. 



obliquity of the joint surfaces between the ulna and 

 humerus, it follows that the fore-arm, wheii in ex- 

 tension, is not in a straight line with the upper arm, 

 but forms with it an angle that opens outwards. 

 Thus, when traction is made upon the entire upper 

 limb from the wrist, some of the extending force is 

 necessarily lost, and such traction, therefore, should 

 be applied from the elbow, as is the usual practice in 

 reducing a dislocation of the shoulder by manipulation. 

 A line drawn through the two condyles will be at 

 right angles with the axis of the upper arm, while it 

 will fonn an angle with the axis of the fore-arm. 

 Thus if we look at the upper arm, the two condyles 

 are on the same level, whereas, when viewed from the 

 fore-arm, the inner condyle lies at a higher level than 

 does the external process. 



The joint line of the elbow is equivalent only to 

 about two -thirds of the width of the entire line 

 between the points of the two condyles. The promi- 

 nence of the condyles forms an excellent point 

 (Kappui- for traction by encircling bands applied 

 to the limb above the elbow joint. At the back of 

 the elbow the prominence of the olecraiion is always 

 to be distinctly felt. It lies nearer the internal 

 than the external condyle. In extreme extension 

 the summit of the olecranon is a little above the line 

 joining the two condyles. When the fore-arm is at 

 right angles with the arm, the tip of the process is 

 below the line of the condyles, and in extreme flexion 

 it lies wholly in front of that line. Between the 

 olecranon and the inner condyle is a depression that 

 lodges the iilnar nerve and the posterior ulnar 

 recurrent artery. 



To the outer side of the olecranon, and just below 

 the external condyle, there is a depression in the skin 

 which is very obvious when the limb is extended. 

 This pit is to be seen even in those who are fat, and 



