AS TO so UNDNESS. 1 1 3 



a big, flat, square hock, he means a hock having these 

 qualities when it is not bent or flexed. What is it that 

 allows our point number ^ to alter its relative position so 

 much ? It is as your anatomy teaches you, the com- 

 paratively small articular lower end of the tibia which 

 gUdes over the large wide and deep articular surface of 

 the astragalus. 



Just one other point to which I must draw your 

 attention. I have told you that all the parts below the 

 lower end of the tibia may be regarded as one structure ; 

 the relative positions of these parts are always the same, 

 hence the articular surface of the astragalus always has 

 the same relative position to the other structures, of 

 which it forms a part — that is to say, it never looks more 

 up or more down, more inside or more outside, without 

 all its belongings altering their positions with it (except 

 in the curby hock) ; so that it follows that when you 

 have not a square hock our point number * approaches 

 point number ^ by the lower articular end of the tibia 

 having glided more or less over the large articular surface 

 of the astragalus, and it follows that the more it does so 

 the nearer does the long axis of the tibia approach the 

 parts beneath it at a right angle. 



In the next place, I wish you to notice what it is that 

 gives size to the hock, or perhaps I ought rather to have 

 said, gives it apparent size. Doubtless you will see that 

 the apparent size depends upon the relative position 

 of our point number * to point number », or in other 

 words, if the articular lower end of the tibia be well 



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