XV.T THE WRIST AND HAND. 275 



fibro-cartilage, which forms the strongest and most 

 important of all the ligamentous connections between 

 the two bones. The synovial sheath of the extensor 

 minimi digiti sometimes communicates with this joint, 

 and may therefore be involved when that articulation 

 is diseased. 



The strength of the wrist joint depends not so 

 much upon its mechanical outline or its ligaments as 

 upon the numerous strong tendons that surround it, 

 and that are so closely bound down to the bones about 

 the articulation. Its strength depends also upon its 

 proximity to the numerous bones and joints of the hand, 

 whereby all movements and shocks are distributed 

 between several articulations. Moreover, in the case 

 of the wrist the long lever does not exist on the distal 

 side of the joint. The movements of the wrist are 

 greatly supplemented by those of the mid-carpal joint. 

 The anterior ligament of the wrist is the strongest 

 ligament of the joint, while the posterior is the 

 weakest. The former structure limits extension, and 

 the latter flexion ^nd in connection with this arrange- 

 ment it is interesting to note that injury fi*om forced 

 extension is' more common than from forced, flexion. 

 Thus; when a man falls upon the hand, he more 

 usually falls upon the palm (forced extension) than 

 upon the dorsum (forced flexion). Owing to the 

 thinness of the posterior ligament, together with the 

 more superficial position of the hinder part of the 

 joint, it follows that the effusion in wrist-joint disease 

 is first noticed at the back of the hand. As the 

 tendons on the front and at the back of the wrist 

 fairly balance one another, the hand in wrist-joint 

 disease shows little tendency to be displaced, but is 

 fixed rather in the mid-position between flexion and 

 extension. It can be understood that in this disease 

 the neighbouring synovial sheaths are readily involved. 



Tn connection with this joint it may be noted 



