370 THE HORSE. 
existing between the three metacarpal bones to the interosseous ligaments 
of the second row. 
4, THE LIGAMENTS COMMON TO THE WHOLE KNEE JOINT are four—two 
lateral, an anterior, and a posterior. 
The external lateral ligament is a thick cord, formed of two kinds of 
fibres, a deep seated and a superficial set, which take a crucial direction. 
It arises from the external lateral process of the radius, and descends 
vertically on the side of the knee joint. In its passage, it gives off a band 
to the pisiform bone, and also to the os unciforme, and terminates at the 
head of the external small metacarpal bone. This ligament lies on the 
carpal bones and capsular ligament. 
The internal lateral ligament, analogous to the preceding, and situated 
on the opposite side, is thicker and larger. It arises from the internal 
lateral process of the radius, and terminates on the supero-anterior and 
internal surface of the large metacarpal and head of the internal small 
metacarpal bones. The fibres of this ligament take a crucial direction ; in 
its passage downwards, it gives off three little bands, namely, one to the 
scaphoid bone, one to the os magnum, and one to the trapezoid. 
The anterior or capsular ligament covers the anterior face of the carpal 
articulations. Its superior edge is attached to the inferior extremity of 
the radius ; its inferior edge is attached to the superior extremity of the 
large metacarpal bone ; its right and left borders are in contact with the 
lateral ligaments ; its external face is connected with tendons, &c.; its 
internal face is lined, at certain points, by synovial membrane. This 
ligament is formed of transverse fibres, more or less oblique, crossed and 
re-crossed, 
The posterior igament—one of the strongest of the animal economy— 
covers the posterior surface of the knee. It is inserted superiorly into the 
transverse ridge which bounds the articular surface of the radius. At the 
posterior part of the carpal bones, it becomes attached to the inner border 
of the pisiform bone, the posterior surface of the os magnum, the cuneiform 
and scaphoid bones terminating on the postero-superior extremity of 
the large metacarpal bone. The scapho-metacarpal ligament, described as 
part of the posterior ligament of the carpo-metacarpal joint, is with 
difficulty separated from this ligament. 
THE KNEE IS THE CENTRE OF TWO VERY EXTENSIVE MOVEMENTS, namely, 
extension and flexion ; to which three others, very limited in their extent, 
may be added, namely, adduction, abduction, and circumduction. 
As already mentioned, all the carpal articulations do not take an equal 
part in the execution of these movements ; in fact, it is evident that they 
chiefly take place in the radio-carpal ginglymus, and in the imperfect 
hinge formed between the two rows of carpal bones. Each of these articu- - 
lations participates in the movements of the knee, nearly in the same 
proportion, the superior perhaps being slightly the more extensive, and 
both perform their office in the same manner. 
In flexion, the first row of bones turns from before backwards on the 
radius ; the inferior row moves in the same way on the superior row. 
The metacarpus is carried backwards and upwards, thus relaxing the 
common posterior ligament. The anterior ligament, on the contrary, is 
rendered tense. The articular surfaces, especially those of the second joint, 
separate in front from one another. 
In extension, the metacarpus is carried below and forwards by an inverse 
mechanism. This movement is arrested when the radius and the meta- 
carpus are placed in the same vertical line, as in the standing position, 
