MYOLOGY 197 



formed by the peculiar arrangement of the two large sesa- 

 moid bones. They are retained in position at this level by 

 a fibrous structure, which forms the metacarpo-phab.ngeal 

 sheath. They then reach the phalanges, being directed 

 obliquely downwards and forwards, as, moreover, the latter 

 are also inclined. Then the tendon of the superficial flexor 

 divides into two slips, which are inserted into the second 

 phalanx, between which slips passes the tendon of the deep 

 flexor, which in its turn goes to be inserted, in the form of an 

 expansion, into the semilunar crest, by which the inferior 

 surface of the third phalanx is divided into two parts.* 



The part which these tendons play is of great importance 

 in the large quadrupeds. 



These tendons, in fact, in addition to the action deter- 

 mined by the contraction of the fleshy fibres to which 

 they succeed, maintain the angle formed by the canon- 

 bone and the phalangeal portion of the hand, and prevent 

 its effacement under the weight of the body during 

 the time of standing. Their strong development, and the 

 position they occupy, make this understood, without it 

 being necessary to insist on it further. 



We mentioned above that the ' tendon ' descends verti- 

 cally from the carpus towards the fetlocks. This is as it 

 should be. But, in some horses, it is oblique downwards 

 and backwards, so that the canon, instead of being of equal 

 depth from before backwards in its whole length, is a little 

 narrower in its upper part. 



This results from the fact that the tendons of the flexors, 

 too firmly bound by the carpal sheath, gradually separate 

 as they pass from the metacarpus, going to join the fet- 

 lock ; hence the obliquity pointed out above. This abnor- 

 mality producing a deleterious result, in the sense that the 

 tendinous apparatus acts with less strength as an organ of 

 support, it constitutes a defect of conformation which is 

 expressed by saying that the tendon has ' failed.' 



Long Proper Flexor of the Thumb {Flexor longus 



* See, as regards this crest, in the paragraph relative to the hoof of the 

 solipeds, the ligures which represent the third phalanx, viewed on its 

 inferior surface (Figs. loi and 102, p. 258). 



