Chap xiiM REGION OF ELBOW. 241 



relations of the olecranon and coronoid process to the 

 liumerus are such that in certain positions the strength 

 of the joint is very considerable. 



The elbow, being a pure hinge-joint, permits only of 

 flexion and extension. These movements are oblique, 

 BO that in flexion the fore-arm inclines inwards, carrying 

 the hand towards the middle third of the clavicle. If 

 it were not for the obliquity of the joint line it would 

 be possible for the hand to be placed flat upon the 

 shoulder of the same side, but this movement is only 

 possible after some excisions of the joint, for in this 

 operation the oblique direction of the articular surfaces 

 is not reproduced. In extreme extension the ulna is 

 nearly in a straight line with the humerus as regards 

 their lateral planes, while in extreme flexion the two 

 bones form an angle of from 30 to 40. 



Bursae. Of the bursse about the joint the large 

 subcutaneous bursa over the olecranon is very 

 commonly found enlarged and inflamed ; and when 

 inflamed may lead to extensive mischief in the limb. 

 Its enlargement is favoured by certain employments 

 involving pressure on the elbow ; thus, the disease 

 known as " miner's elbow " is merely an enlargement 

 of this sac. There is a bursa between the biceps 

 tendon at its insertion and the bone, the relations of 

 which to the nerves of the fore-arm are worth noting. 

 A case, for instance, is reported where this bursa 

 became chronically enlarged, and by pressing Tipon the 

 median and posterior interosseous nerves produced 

 loss of power in the fore-arm (Agnew). 



Of the ligaments of the elbow joint the anterior 

 and posterior are comparatively thin, and the latter 

 especially soon yields to the pressure of fluid within 

 the joint in disease of the articulation. The internal 

 lateral is the strongest and most extensive of the 

 ligaments of the pai-t. From its rigidity, its extended 

 attachment, and the fact that it serves to limit not 



Q 4 



