228 THE EXTERIOR OF THE HORSE. 



without the region, and forms behind a more or less pronounced elevation under 

 the skin. 



Several special ligaments, short, strong, and numerous, unite the bones of the 

 same row to one another ; others maintain the two rows in contiguity, or concur 

 to fix the one or the other to the forearm or the canon ; finally, the common liga- 

 ments, which are much longer and more resisting, and common to all the carpal 

 articulations, appear to assume the role of insuring general solidity of the whole 

 region. 



Among the last, two are lateral, funicular, which circumscribe the carpus 

 within and without, and extend from the tuberosities of the radius to termi- 

 nate on the head of the rudimentary metacarpals ; the other two are capsular : 

 the one, the anterior, is thin, more particularly charged to sustain the synovial 

 membrane of the joint and to furnish gliding surfaces for the tendons which 

 pass over the anterior surface of the knee ; the other, the posterior, much more 

 fibrous, extremely thick and resisting, fills up all the irregularities on the pos- 

 terior face of the carpal bones and transforms this face into a veritable sheath, 

 the carpal sheath, which is completed posteriorly by the supra-carpal bone and 

 an arch of fibrous tisssue, in which are lodged the flexor tendons of the pha- 

 langes. This ligament, one of the most powerful in the organism, is prolonged 

 at its inferior extremity by a strong band to constitute the check tendon, Avhich is 

 inserted into one of these tendons (that of the deep flexor), and plays a mechan- 

 ical but important role in supporting the fetlock and maintaining its angle. 



Three synovial membranes lubricate the articular surfaces and facilitate their 

 movements. They are everywhere firmly surrounded by the ligaments as well as 

 the extensor tendons of the foot, excepting at certain places where they are more 

 feebly supported, and become the seat of abnormal dilatations. We will refer to 

 these in discussing the blemishes. 



The anterior face of the carpus is traversed from above to below by two 

 principal tendons, which are maintained there by means of special synovial 

 sheaths : one of them is that of the anterior extensor of the metacarpus, the other 

 that of the anterior extensor of the phalanges. 



The external face is traversed by the tendon of the lateral extensor of the 

 phalanges ; the internal face by that of the internal flexor of the metacarpus. 



Finally, upon the posterior face of the region is located the vast carpal 

 sheath, whose synovial membrane covering its walls and reflected upon the two 

 tendons of the flexors of the phalanges, ascends on the posterior face of the 

 radius to about its inferior fourth, and descends against the metacarpus to the 

 lower limit of its superior third. Although strongly surrounded above by the 

 muscular cone of the flexors of the metacarpus and the antibrachial aponeurosis, 

 below and in its middle portion by the carpal arch, it nevertheless becomes 

 apparent, when it is the seat of abnormal distentions in the form of tumors, whose 

 exact characteristics and situation we will indicate farther on. 



The movements of the canon on the forearm mechanically excite those 

 of the knee ; they consist of flexion and extension. 



The first is produced when the foot is elevated from the ground and before 

 it is advanced to complete the step. It is worthy of remark that the inferior 

 extremity of the member, instead of moving in its own plane, is deviated out- 

 ward in consequence of the obliquity of all the articular surfaces, and is not thus 

 exposed to come in contact with the posterior face of the forearm. 



