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PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



axis of the fore leg occurs through the flexion of the knee-joint, which is 

 elevated and advanced by the action of the coraco-radial and humero- 

 radial muscles ; then by the action of the flexors of the carpus and digit 

 the fetlock and pastern-joints are flexed. 



FIG. 301. POSTERIOR EXTREMITY OF THE 

 HORSE IN EXTENSION. (Colin). 



A B, line of action of gluteus medius. C D, line of 

 action of triceps extensor. E F, line of action of gas- 

 trocnemius. G H, line of action of metatarsal flexor. 



FIG. 302. ANTERIOR EXTREMITY OF THE 

 HORSE IN EXTENSION. (Colin). 



AD, BD, and CD. lines of action of the triceps exten- 

 sor brachii, scapulo-ulnaris, and aconeus muscles. E f. 

 flexor brachii. G H, line of action of flexor pedis mus- 

 cles. 



Extension of the fore leg is the reverse of the preceding motions 

 and serves to open out the angles reduced in flexion and so increase the 

 length of the axis of the limb. Extension is still further the reverse of 

 flexion in that the motion commences in the pastern-joint, instead of in 



