456 THE EXTERIOR OF THE HORSE. 



employment is still more difficult, for, not having perfect freedom in 

 the use of his fore-limbs, and being predisposed to stumble, he exposes 



his rider to falls which may prove 

 serious on rough and uneven roads. 



b. Axes of the Posterior Members. 



Axes viewed in Profile. The 

 principle which we have employed to 

 establish the axes of the anterior mem- 

 ber admit of a much simpler applica- 

 tion when referred to the posterior 

 member. The centre of suspension of 

 the latter upon the trunk is known to 

 us with sufficient accuracy ; it is the 

 cbxo-femoral articulation. We may 

 therefore conclude that the direct axis 

 of the posterior column will be in a 

 good position if the digital extremity 

 of this column is stationed at the bot- 

 tom, d (Fig. 162), of the vertical line 

 which passes through the articular cen- 

 tre, c. In fact, it is this which obser- 

 vation demonstrates in horses of good 

 equilibrium of the posterior quarters ; 

 a plumb-line placed at the level of the 

 joint in question divides the hoof into 

 two equal parts. 



As in the anterior member, and for the 

 same reasons, the vertical line, cd, is also 

 equidistant from the perpendiculars to the 

 ground, ot and s/>, or also ef and jh. It 

 intersects the leg, os, as well as ej, at its 

 middle. If the tarso-metatarsal segment 

 remain vertical, the horizontal projection, 

 //>, of the leg is double the horizontal projec- 

 tion, dp, of the phalangal segment. Finally, 

 any degree of opening of the angles will be 

 compatible with good axes, on condition 

 FIG. 162. that the articular angles maintain their 



summits upon the vertical lines ot and sp. 



The axes of the hind-limbs are based, as is seen, upon the same 

 principles as those of the fore-limbs. The four locomotory columns, in 



