290 THE EXTERIOR OF THE HORSE. 



Fractures of the canon, though rather common, are, so far as our study is 

 concerned, absolutely deprived of interest. We should, nevertheless, mention 

 some : they are those of the rudimentary metacarpal or metatarsal bones. 

 Resulting from traumatisms, they give rise to a complication, similar to the for- 

 mation of a splint, at the point of union of the two osseous segments. 



As to the synovial dilatations of the canon, they properly belong to either of 

 the regions between which the canon is situated. The superior have already 

 been pointed out with the knee ; they are due to an abnormal distention of the 

 carpal sheath. The inferior, known under the name of windgalls, consist of a 

 hydropsy of the synovial membrane of the metacarpo-phalangeal articulation, or 

 of the great sesamoid sheath, and will be studied with the fetlock. 



Finally, .there are also found, along the length of the canon, traces of actual 

 cautery of varying area and configuration, which indicate, according to their situ- 

 ation, that the animal has been treated for disease of the osseous apparatus, the 

 tendons, or the synovial membranes. In spite of these markings, the alterations 

 of which they are the evidence may not have disappeared, and it is wise, conse- 

 quently, to submit the member which presents them to a minute examination. 

 In any case, the horse has none the less lost at least a part of his value, for he 

 is blemished, and so much more gravely as the treatment to which he has been 

 subjected has been less efficacious. 



G.— The Fetlock. 



Situation ; Limits ; Anatomical Base. — The fetlock is situ- 

 ated between the canon and the pastern. It supports, at its posterior 

 part, a horny production, the ergot, and a tuft of hair to which has been 

 given the name of footlock. 



It has for its anatomical base the metacarpo- or the metatarso-phalangeal 

 articulation, which results from the apposition of the inferior extremity of the 

 principal bone of the canon and the superior extremity of the first phalanx, 

 complemented behind by the great sesamoid bones (Fig. 96). 



These bones are united by numerous ligaments : an anterior or capsular ; two 

 lateral funicular, a; a posterior, the suspensory of the fetlock, which has already 

 been mentioned, and whose two branches terminate upon the sesamoid bones, a 

 (Fig. 97) ; finally, the group of inferior, b (Fig. 97), and lateral, b (Fig. 96), 

 sesamoid ligaments, short and strong, which fix these bones to the first phalanx 

 and the canon. The two sesamoid bones are, moreover, intimately united to 

 each other by means of a fibro-cartilaginous mass which transforms their poste- 

 rior face into a pulley, c (Fig. 97), upon which the flexor tendons of the phalanges 



glide. 



This ligamentous apparatus, of great strength, is, in addition, reinforced by 

 the extensor tendons of the phalanges in front, and by the flexor tendons behind, 

 which also fulfil the role of suspensors like the superior sesamoid ligament, 

 whose function they supplement. 



Three distinct synovial membranes exist in the region of the fetlock : one 

 articular and two tendinous. 



The first, firmly maintained in front and on the sides, can become dilated 



