ANATOMY OF THE HORSE. 
663 
Attachment. —Superiorly, (and in common union with the fol¬ 
lowing- muscle) to the lower side of the internal condyle: infe- 
riorly, to the upper and back part of the os coronse. 
j Relations. —Posteriorly, to the three flexores metacarpi and 
flexor sublimis; anteriorly, to the radius and flexor profundus. 
Along* the antero-internal border run the radial blood-vessels 
and nerves. 
Structure. —The superior attachments of the mass of muscle 
(common to this and the perforans) are in part fleshy, but prin¬ 
cipally tendinous: the tendinous part being* underneath and 
applied to the trochlea of the condyle, which in the motions of 
the joint it plays over. The mass is divisible (more or less 
completely) into three or four or more distinct portions, whose 
surfaces are partly aponeurotic, and w hose interiors (with the 
exception of the one next the radius, which is commonly the 
most completely separable) are intersected w ith layers of ten¬ 
don. Just above the knee it contracts its substance and be¬ 
comes tendinous, forming* two flattened tendons which pass down 
under the posterior annular ligaments. The posterior of these 
tendons, the tendo perforatus, is neither so broad nor so flat as 
the other; it presents a concave surface anteriorly, to embrace 
its companion in front. At the back of the fetlock joint, it ex¬ 
pands so as more completely to cover the perforans, and sends 
off a crescentic process which surrounds that tendon. At this 
part also a tendinous theca includes both tendons, having at¬ 
tachments on each side to the sesamoids. Opposite to the small 
pastern joint, the perforatus splits into two divisions, having* the 
perforans passing between them: the triangular interval left is 
occupied by a portion of membrane which is so attached as to 
form a circumscribed synovial bag. 
Action. —To bend the fetlock and pastern joints ; and also to 
assist in the flexion of the knee. 
flexor pedis perforans.— Epicondylo-phalangeus . 
Situation , form , and superior attachment. —The same as the 
preceding*. 
Inferior attachment , to the posterior concavity of the os pedis. 
Structure. —The fleshy origins and bellies of this muscle are 
confounded with those of the perforatus. As they approach the 
knee, however, they separate; and then the perforans runs im¬ 
mediately behind the perforatus. At the knee, like its fellow, it 
is wholly tendinous, and here indeed partakes somewhat of the 
nature of cartilage, as it passes through the same synovial bag 
as encloses its companion. Below the knee, these tendons as¬ 
sume different shapes; the perforans being cylindroid, the other 
