The Skeleton. 13 



ends which enter into and form the various joints; as a 

 result certain motions take place between bones, to 

 describe such movements the terms flexion and extension 

 are used, thus a limb is said to be be flexed when bent, 

 extended when straightened out. 



The shoulder blade is flat and triangular in shape, 

 with a spine on its outer surface, each side of the spine 

 in the depressions thus formed are lodged muscles, which 

 asisst in supporting the shoulder joint. The develop- 

 ment of these muscles is important when we consider the 

 wearing properties of the shoulder and its liability to 

 collar galls, etc. The position or slope of the shoulder 

 blade is of interest to note, because the slope of this 

 bone is indicative, to a certain extent, of the positions 

 taken by the bones below, e. g., in the light horse in 

 which a great deal of action is required, there must be a 

 sloping shoulder, such a condition increasing the elasticity 

 of the gait and thus diminishing concussion. On the 

 other hand, in the draft horse a more upright shoulder 

 is preferred, so as to bring a good bearing surface into 

 the collar, consequently we notice in the heavy horse a 

 more upright shoulder and pasterns than in the light 

 horse. 



In the dairy cow the slope of the shoulder blades are 

 towards one another at their tops, thus giving one of the 

 wedges of the triple-wedge desired by dairymen. The 

 lower end of the shoulder blade, together with the upper 

 end of the arm, forms a shallow ball and socket joint, 

 one in which there is considerable play. This joint, like 

 all the others, is surrounded by what is known as the 

 capsular ligament, from which is secreted the joint oil 



