114 THE MECHANICAL FUNCTIONS OF THE FOOT. 



surfaces of the bones, and, owing to their method of origin and 

 insertion and their radiating formation, to be capable of assuring 

 the relative position of the bones forming the joints without 

 the intervention of other structures. The justice of this theo- 

 retical deduction is shown by the fact that, after section of 

 the flexor pedis perforans and perforatus, the angle between 

 the metacarpus and os suffraginis often remains little 

 altered. 



The joints named, and especially the pedal joint, are further 

 supported in position by tendons, particularly by the flexor 

 tendons, with their limiting and encircling ligaments. 



Immediately the foot comes in contact with the ground the 

 ligaments and tendons are thrown into tension, the position of 

 the hoof remaining the same from the beginning to the end of 

 this period. We see that the articular depression of the pedal 

 joint forms the point of rotation for the termination of the 

 column of bones carrying the weight of the body. We see, 

 also, that, varying with the weight carried by the limb, the 

 fetlock joint moves to a certain extent backwards and down- 

 wards, though it returns again immediately the load diminishes, 

 and that while the fetlock has full play the hoof remains 

 stationary. This play of the fetlock would be impossible were 

 the pedal joint immovably connected with it. 



The strain on tendons and ligaments is not, however, equally 

 severe throughout these joints at all times, but tension and 

 relaxation alternate according as the axis of the fetlock is 

 more or less inclined to the horizontal plane. At the moment 

 when the fetlock is most oblique, all the ligaments of the 

 fetlock joint, and especially the superior suspensory ligament 

 and the perforans and perforatus tendons, are exceedingly 

 tense. The ligaments of the pedal joint, on the other hand, 

 are relaxed. But just before the hoof leaves the ground, all 

 the ligaments of the pedal joint become tense to their extreme 

 margins. At this moment, in consequence of the forward 

 movement of the body, the foot is tilted, but the flexor muscles 

 do not begin to act fully until the toe of the foot quits the 

 ground. As the weight diminishes, the suspensory ligaments 

 of the navicular bone, the four posterior corono-suffraginal 

 ligaments, the ligaments passing between the lateral cartilages 

 and skin of fetlock, constituting the plantar aponeurosis, and 



