io6 THE ARTISTIC ANATOMY OF ANIMALS 



latter being much more limited than the former. There is 

 also rotation. 



By flexion, the inferior extremity of the femur is directed 

 forwards ; the bone of the thigh then takes a more oblique 

 direction than the normal. This movement takes place, for 

 example, when the animal carries forward one of its hinder 

 limbs. Extension, which takes place in an inverse sense, is 

 produced when the foot is fixed on the ground, while the 

 body is projected forward. It is also produced in the 

 action of kicking. 



As for the lateral movements — viz., abduction and ad- 

 duction — they are less extensive than the preceding move- 

 ments. The absence of the pubio-femoral ligament in other 

 quadrupeds than the horse explains why in them abduction 

 is less limited than in the latter. Indeed, it is the tension of 

 this ligament, occasioned by the abduction of the thighs, 

 which arrests more quickly the movement in question. 



Articulation of the Knee. — This articulation, as in man, 

 is formed by the femur, the patella, and the tibia. 



In the horse the ligament of the patella is not single, but 

 consists of three parts, designated, on account of their 

 position, by the respective names of external, internal, and 

 median patellar ligaments. The two former come from the 

 angles on the corresponding borders of the knee-cap ; the 

 median springs from the anterior surface and inferior angle of 

 the same bone. They all three pass to their termination on 

 the anterior tubercle of the tibia. The external ligament 

 is the strongest, and the internal ligament the least 

 developed. 



In the dog, the cat, the pig, and the sheep, the patellar 

 ligament consists of a single band. The articulation is 

 further strengthened on the sides by lateral ligaments — an 

 internal and an external. 



With regard to the principal movements, these are flexion 

 and extension, to which may be added movements of rotation 

 of limited extent. In flexion, the leg bends on the thigh ; 

 its inferior extremity is directed upwards and backwards ; 

 the angle which the tibia naturally forms with the femur 

 becomes less obtuse. 



