POSTERIOR MEMBER. 279 



A jarde is far from offering the same gravity as spavin. This is simply due 

 to the fact that it never terminates in anchylosis of the inferior tarsal articula- 

 tions ; the latter remain absolutely intact. 



The lameness which it determines, when the work of ossification has been 

 completed, depends upon the want of freedom experienced by the small metatarsal 

 arthrodia or the compression of the suspensory ligament of the fetlock and the 

 flexor tendons. 



Osteophytes. — The hock does not always present so clear a delimitation 

 of its osseous blemishes ; in old horses it is quite frequently the seat of dissemi- 

 nated bony deposits whose point of origin may be in the thickness of the ante- 

 rior capsular ligaments, that of the lateral ligaments, or again in that of the 

 articular and tendinous synovial membranes. This condition, as we have seen, 

 is the ultimate complication of synovial dilatations, and, consequently, is nothing 

 remarkable. The normal profiles of the hock, in such instances, are completely 

 changed. At the level of these osseous tumors the region presents more or less 

 voluminous, hard, and irregular reliefs, which have a great tendency to join and 

 eventually encircle the tarsal apparatus. These are always conclusive evidence 

 of ruin and of usage driven to its utmost limits. 



E.— The Chestnut. 



The chestnut, o (Fig. 77, B and D), in the posterior member, is 

 situated on the inferior part of the internal surface of the hock. It 

 responds anatomically to the small cuneiform, and is sometimes wanting. 

 Huzard the elder has mentioned its absence, and we have also verified 

 it in several instances. In such a case the description of the horse 

 should mention the fact. As in the anterior member, its area and 

 volume vary in a great measure according to the race ; it has, besides, 

 nothing of special interest. 



(The chestnut, anatomically, is the rudiment of the hoof of the 

 fifth digit or thumb, which it represents. Its absence is most fre- 

 quently noticed in meridional horses, probably the descendants of the 

 African horse, which, of all the equine races, is the most closely related 

 to the ass. It is smaller in well-bred horses. — Harger.) 



F. — The Canon and the Tendons. 



Situation ; Limits ; Anatomical Base. — The canon is the 

 region of the members which extends vertically from the hnee or the 

 hock to the fetlock. 



Its anatomical base consists of the three metatarsal or metacarpal bones, the 

 tendons of the different motor muscles of the phalanges, and a very strong liga- 

 ment, known, on account of its fiinctions, under the name of the suspensory 

 ligament of the fetlock. 



