POSTERIOR MEMBER. 



291 



behind and above, between the canon bone and the suspensory ligament of the 

 fetlock ; behind and below, upon the sides of the first phalanx. 



The largest of the tendinous synovials, posterior to the articulation, subserves 

 the gliding of the tendons against the sesamoid pulley ; it is known by the name 



FiG. 96. 



Fig. 97. 



of great sesamoid sheath. Extending from the inferior third of the canon to the 

 superior part of the second phalanx, and unequally sustained by the surrounding 

 tissue, it sometimes forms a dilatation on each side, above the fetlock, between 

 the suspensory ligament and the flexor tendons. It presents, also, along the 

 length of the pastern, two weak points, of which we will only make mention, 

 and whose enlargement is always much less marked than that of the preceding. 

 The second and the smallest of the tendinous synovials is found in front, 

 underneath the tendons of the extensors of the phalanges, and permits their 

 gliding upon the anterior face of the capsular ligament. It is extremely rare 

 that it communicates with the articular synovial membrane. It is susceptible of 

 becoming distended over its whole periphery, unsustained by the tendons, and 

 even of rupturing its parietes into the surrounding connective tissue under the 

 influence of internal pressure. 



Mechanism of the Articulation of the Fetlock. — By rea- 

 son of the oblique direction of the first phalanx and of its superior 

 articular surface, which play, with regard to the weight of the body, 

 the role of an inclined plane, the principal bone of the canon constantly 



