250 THE HORSE, 



VI The tendon of the perforating flexor inserted into the coffin-houe, after having 

 passed over the navicular bone. 



n The seat of the navicular joint lameness. 



The inner or sensible frog. 



2^ The cleft of the horny frog. 



q A ligament uniting the navicular bone to the smaller pastern. 



r A ligament uniting the navicular lione to the coftin-bone. 



s The sensible sole, between the coffin-bone and the horny sole. 



t Tlie horny sole. 



u The crust or wall of the foot. 



V The sensible laminae to which the crust is attached. 



7v The coronary ring of the crust. 



cc The covering of the coronary ligament from which the crust is secreted. 



z Place of bleeding at the toe. 



It will be easy to perceive, from this description of the situation of the 

 suspensory ligament, why splints placed backward on the leg are more 

 likely to produce lameness than those which are fovmd on the side of the 

 leg. They may interfere with the motion of this ligament, or, if they are 

 large, may bruise and wound it. 



The principal action of these ligaments is with the sessamoid bones, 

 which they seem to suspend in their places, and they are therefore called the 

 suspensory li^ments. The pasterns (see cut, p. 249) are united to the 

 shank in an oblique direction, differing in degree in the different breeds of 

 horses, and in each adapted to the purpose for which that breed was de- 

 signed. The weight falls upon the pastern in the direction of the shank- 

 bone, and the pastern being set on obliquely, a portion of the weight must 

 be communicated to the sessamoids. Much jar is saved by the yielding of 

 the pasterns, in consequence of their oblique direction ; and the concus- 

 sion which would be produced by that portion of weight which falls on 

 the sessamoid-bones is completely destroyed, for there is no bone under- 

 neath to receive it. They are suspended by this ligament — an elastic 

 ligament, which gradually yields to, and is lengthened by, the force im- 

 ]3ressed upon it, and in this gradual yielding and lengthening, all painful or 

 dangerous concussion is rendered impossible. 



If the ligament lengthens, the sessamoid-bones must descend when the 

 weight is thrown on them, and it would appear that they do so. If the 

 thorough-bred horse with his long pasterns is carefully observed as he 

 stands, the tuft at the fetlock will be some inches from the turf ; but when 

 he is in rapid motion, and the weight is thrown violently on this joint, the 

 tuft descends and sweeps the very ground. This, however, is the combined 

 action of the fetlock and pastern-joints, and the sessamoid-bones. The 

 sessamoids do not actually descend ; but they revolve, they partly turn over. 

 The strong ligament by which they are attached to the pastern-bone acts as 

 a hinge, and the projecting part of the bone to which the suspensory liga- 

 ment is united, turns round with the pressure of the weight; and so that 

 part of the bone becomes lower. How is it raised again? Tliis ligament, 

 strangely constructed as a ligament, is elastic. It yields to the force im- 

 pressed upon it, and lengthens ; but as soon as the foot is lifted from tlie 

 ground, and the weight no longer presses, and the force is removed, its 

 elastic power is exerted, and it regains its former dimensions, and the ses- 

 samoid-bone springs back into its place, and by that forcible return assists 

 in raising the limb* 



* Mr. Percivall very clearly describes this : ' Fm'lhermore it seems to us that these 

 elastic parts assist iu the elevatigu of the feet from the ground iu those paces in which 



