90 FORM AND ACTION. 



erring to throw the limb forward, and the continuance of the same 

 act it is, enforced by additional powers, which propels the machine 

 in progression. A well-formed stifle is, therefore, a point of some 

 importance, and the best-formed joint of this description is that 

 which, from the sharpness of the angle between the femoral and 

 tibial bones, is forced well forward and upward towards the body, 

 and at the same time discloses through the skin the prominence of 

 the patella, but particularly that of the rectus muscle above it. 

 The prominence of the stifle, it is evident, must depend upon the 

 obliquity of the position of the femoral bone, and the sharpness 

 of the angle formed between it and the tibia : in one instance, 

 the stifle will appear bold and obtrusive, abutting almost against 

 the belly ; in another, it will be seen situated low down upon the 

 thigh, quite away from the belly; and this latter is the stifle of all 

 others which indicates, as far as it and its connexions are con- 

 cerned, want of power and action in the hind quarter. 



THE THIGH, OR GASKIN. 



What horse-persons now understand by the thigh of the horse 

 is the part between the stifle and hock joints; a part, anatomically 

 regarded, that corresponds to the human leg. In the young animal 

 it is composed of two bones ; but these bones are united by an 

 elastic (cartilago-ligamentous) substance which, as the animal ap- 

 proaches the adult period, becomes gradually converted into osseous 

 matter, until at length the two bones become in reality one and the 

 same solid structure ; so that in every horse of full growth it would 

 be but in accordance with truth to say, the thigh was composed of 

 a single bone. The tibia presents upon its superior end two ovoid 

 superficial depressions, which are, by the addition of cartilaginous 

 interventions, rendered deeper and better adapted to receive the 

 condyles of the femoral bone, the one moving upon the other in 

 extension and flexion, and having some little lateral motion. The 

 lower end of the tibia is smaller than the superior, the bone taper- 

 ing rather from top to bottom, and is shaped so as to accommodate 

 itself to the construction of the hock-joint. 



The chief considerations touching the thigh or gaskin are, its 

 position, its length, and its thickness or muscularity. In accord- 



