238 THE EXTERIOR OF THE HORSE. 



from the posterior ischio-tibial muscles, and wWch is known under the pictu- 

 resque name of furrow of misery. 



The internal surface, called the/ai! of the thigh, is also more or less convex. 

 It is traversed above in its direction and from back to front by a large vein, the 

 saphena, on which phlebotomy is sometimes practised. This vein is accompanied 

 by a small artery bearing the same name and covered over with a net-work of 

 nerve-branches and of lymphatic vessels, whose situation it is important to re- 

 member from a surgical point of view. 



The anterior border of the thigh is constituted by a voluminous muscular 

 mass, the crural triceps, whose function it is to extend the leg. Over the middle 

 and inferior portion of this border attaches a musculo-cutaneous fold, which is- 

 called the fold of the stifle, and spreads over from the side of the flank to the 

 anterior surface of the stifle-joint. 



As to the posterior border, it represents by itself the sub-region of the 

 buttock or the breeching, and has for its base the ischio-tibial muscles. It 

 describes, beginning at the base of the tail where it becomes continuous with the 

 croup, a regularly-curved line, which becomes concave inferiorly and disappears 

 at the posterior border of the leg. The most salient point of this graceftil curve 

 has received the name oi point or angle of the buttock; it is due to the prominence 

 of the ischiatic tuberosity of the coxa. On the other hand, the, fold of the buttock 

 is the most concave portion of this line, and corresponds about to the centre of 

 flexion of the tibia on the femur. It is worthy of remark that in very emaciated 

 subjects the point and the fold of the buttock are always strongly marked, while 

 they are scarcely indicated in those that are in good condition, particularly in 

 the heavy draught-horse, whose muscular system is voluminous. 



Viewed from behind, the thigh is thicker as its muscular masses are more 

 developed and as the animal belongs to a race of a more lymphatic and less 

 nervous temperament. 



Movements.— This region, in relation with the movements 

 which it executes, is most interesting to study. It describes two prin- 

 cipal movements, whose centre is the coxo-femoral articulation : these 

 are extension and flexion. Their maximum amplitude is about 30 

 degrees. 



During flexion, the femur is displaced angularly to begin the step. 

 It reaches its limit of flexion a little before the foot arrives on the 

 ground, so as to allow the full extension of the tibia, which has not yet 

 been completed at the moment that the femoral flexion is accomplished. 



During extension, the phenomena have an inverse order : the femur 

 moves backward, thus strongly opening the coxo-femoral angle; its- 

 obliquity is changed in direction ; it becomes vertical or even inclined 

 backward and downward when the limb is about to rise. The exten- 

 sion of the thigh takes place during the last phase of contact and 

 ceases as soon as the foot has left the ground to accomplish a new step. 

 The muscles which execute it are more numerous and stronger than 

 those which produce flexion ; a fact not to be wondered at, since these 



