RINGBONE 



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There are only two ligaments of the pastern joint, these are the outer 

 and inner lateral ligaments. They are attached superiorly to the lateral 

 aspects of the inferior extremity of the os sufFraginis and inferiorly to the 

 sides of the os corona. These lateral ligaments are continued downwards 

 and backwards, and their prolongations form part of the postero-lateral 

 ligaments of the corono-pedal joint. The pastern joint has a single 

 synovial membrane, which is supported anteriorly by the posterior surface 

 of the extensor pedis tendon, since this joint has no anterior common 

 ligament, and the tendon referred to takes its place. The lateral ligaments 

 support the sides of the membrane, and the complementary cartilage 

 supports it behind ; but above the cartilage the membrane projects as a 

 small pouch in front of the superficial inferior sesamoidean ligament. The 

 pastern joint is capable of flexion and extension. 



DISEASES OF THE PASTERN JOINT 



RINGBONE 



This is a term which is frequently used to indicate quite a number 

 of diseased conditions affecting the pastern joint or the parts surround- 

 ing it, such conditions being characterised by the appearance of an 

 enlargement of the part. 



Thus the name is given to exostoses which appear on the long pastern 

 bone, and which may be quite clear of the articulation, and upon which 

 they may not encroach. Owing to the fact that such exostoses are some- 

 what of the nature of splints and do not interfere with the action of the 

 joint, they are frequently either excluded from the term ringbone altogether 

 or designated false ringbones. This is quite a rational method of classifying 

 them, as Hunting has so frequently maintained, for they are nothing like 

 such serious affections as those conditions which in this classification are 

 termed true ringbones. In these latter the articulation itself is affected, 



