FETLOCK JOINT. 371 
In flexion, the bony radii do not directly approach each cther; 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 plain 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 the 
knee ; but it favours them by permitting the carpal bones to change their 
reciprocal connexions, and thence lends itself, through the medium of the 
radio-carpal and inter-carpal ginglymi, 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 correspond- 
ing surfaces on the large metacarpal bone. 
An 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-METACARPAL ARTICULATIONS allow only of a very slight 
vertical sliding 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 condyles of the same metacarpal bone. It is 
a perfect hinge. 
The ligaments forming the bond of union between these surfaces are as 
follow :—First, those which belong to the ossa sesamoidea ; secondly, those 
which connect the os corone 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 
inter-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-cartila- 
ginous mass, which completes behind the superior articular surface of the 
os corone, it continues slightly expanding as it ascends, until it reaches 
the bases of the ossa sesamoidea, to which it is inserted, mixing also with 
the inter-sesamoideal ligament. Zhe middle is of a triangular shape, and 
is formed of three bands, two lateral and a median. It is often confounded 
with the first igament, although easily distinguishable from it by its lower 
insertion. Fixed in common, inferiorly, to the apex of the triangular 
ridge situated on the posterior surface of the os suffraginis, these three 
bands diverge, the two lateral to be attached to the bases of the ossa 
sesamoidea, the median becoming confounded with the surroundiny liga- 
ments, Zhe deep-seated ligament is formed by two little bands, hidden by 
BB2 
