FETLOCK JOINT 415 



mechanism. This movement is arrested when the radius and the meta 

 carpus are placed in the same vertical line, as in the standing position. 



In flexion, the bony radii do not directly approach each other ; the 

 inferior extremity of the metacarpus is always carried outwards. The 

 movements of abduction, adduction, and circumduction are not able to be 

 performed until the foot is bent up under the fore-arm, and are then only 

 capable of being very partially carried out. 



The jjlain arthrodial surfaces existing between the lower row of carpal bones 

 and the superior metacarpal extremity, only admit of a simple sliding of 

 the surfaces in contact. The limited motion of this articulation can have 

 but a secondary influence over the general movements of tlie knee ; but it 

 favours them by permitting the carpal bones to change their reciprocal 

 connections, and thence lends itself, through the medium of the radio-carpal 

 and inter-carpal gingl3^mi, to a more exact coaptation of the articular surfaces 

 which constitute them. 



INTER-METACARPAL ARTICULATIONS 



Each small metacarpal bone articulates with the large metacarpal bone 

 through the medium of two diarthrodial surfaces, situated on the inner 

 part of their heads ; a third, of a synarthrodial character, occurs on the 

 anterior part of the body. Each of these articulates with corresponding 

 surfaces on the large metacarpal bone. 



All interosseous ligament, composed of very short and strong bundles, is 

 interposed between the synarthrodial surfaces, and fixes them solidly one on 

 the other. 



The inter-metacaepal articulations allow only of a very slight 

 vertical slidina: movement. 



FETLOCK JOINT 



The fetlock joint is formed by the junction of the inferior condyloid 

 extremity of the large metacarpal bone with the biconcave surface of the 

 OS sufFraginis, and by the anterior smooth surfaces of the ossa sesamoidea 

 with the posterior part of the cond^des of the same metacarpal bone. Ic is 

 a perfect hinge. 



2'he ligaments forming the Ijond of union between these surfaces are as 

 follow : — First, those which belong to the ossa sesamoidea ; secondly, those 

 which connect the os coronse and pastern together ; thirdly, a ligament 

 common to both. Besides which, there is a synovial capsule. 



1. The first have received the general names of the sesamoideal liga- 

 ments, and are six in number, namely, three inferior, two lateral, and an 

 i n ter sesamoideal. 



The inferior sesamoideal ligaments are divided into three, namely, the 

 superficial, the middle, and the deep. Of these the first is a narrow band, 

 flattened behind and before ; arising from the middle of the fibro-cartilagin- 

 ous mass, which completes behind the superior articular surface of the os 

 coronse, it continues slightly expanding as it ascends, until it reaches the 



