346 THE SUSPENSORY LIGAMENTS. 



/ The extensor tendon inserted into both the pasterns and the coffin-bone. 

 m The tendon of the perforating flexor inserted into the coffin-bone, after having paused 

 over the navicular bone. 



n The seat of the navicular joint lameness. 



o The inner or sensible frog. 



p The cleft of the horny frog. 



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



r A ligament uniting the navicular bone to the coffin-bone. 



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



t The horny sole. 



The crust or wall of the foot. 



v The sensible laminae to which the crust is attached. 



w The coronary ring of the crust. 



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



z Place of bleeding at the toe. 



At the back of the shank just helow the knee, and in the space between the 

 two splint-bones, is found an important ligament, admirably adapted to ob- 

 viate concussion. It originates from the head of the shank-bone, and also 

 from the heads of the splint-bones; then, descending down the leg, it fills 

 the groove between the splint-bones, but is not attached to either of them. A 

 little lower down it expands on either side, and, approaching the pasterns, bifus- 

 cates, and the branches are inserted into two little bones found at the back of the 

 upper pastern, one on each side, called the sessamoid bones. (See page 345, 

 and in this cut which represents the pastern and foot, sawn through the centre.) 

 The bones form a kind of joint both with the lower head of the shank-bone and 

 the upper pastern-bone, to both of which they are united by ligaments (i and g\ 

 but much more closely tied to the pastern than to the shank. The flexor tendons 

 pa'ss down between them through a large mucous bag to relieve them from the 

 friction to which, in so confined a situation, they would be exposed. The sus- 

 pensory ligament is continued over the sessamoids, and afterwards obliquely 

 forward over the pastern to unite with the long extensor tendon, and downward 

 to the perforated tendon, which it surrounds and fixes in its place, and also to the 

 smaller pastern-bone. 



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

 pensory ligament, why splints placed backward on the leg are more likely to 

 produce lameness than those which are found on the side of it. 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 

 ligaments. The pasterns (see cut p. 345) 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 designed. The weight falls 

 upon the pastern in the direction of the shank-bone, and the pastern being sot 

 on obliquely, a portion of that weight must be communicated to the sessamoids. 

 Much concussion is saved by the yielding of the pasterns, in consequence of their 

 oblique direction ; and the concussion which would be produced by that portion 

 of weight which falls on the sessamoid bones is completely destroyed, for 

 there is no bone underneath to receive it. They are suspended by this liga- 

 ment an elastic ligament, which gradually yields to, and is lengthened by, the 

 force impressed upon it, and in this gradual yielding and lengthening, materi- 

 ally lessening, or generally preventing, all painful or dangerous concussion. 



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 niches 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 



