332 HEALTH AND DISEASE 



which proceeds downwards to the foot. In its course it passes, in com- 

 pany with the flexor pedis perforatus tendon, over the back of the 

 knee, where it is bound down by the carpal sheath and lubricated with 

 synovia. Below the knee it is joined by a strong fibrous band, the check 

 ligament or inferior carpal ligament. Thence it continues downward 

 behind the canon, over the fetlock -joint, where it is encircled by a 

 tendinous offshoot from the perforatus. Behind the pastern it passes 

 between the divided tendon of the flexor pedis perforatus, and ultimately 

 enters the foot, where, after widening out beneath the navicular bone, it 

 becomes inserted into the under surface of the os pedis. 



Action. To flex the pastern on the fetlock, and through it the knee also. 



Lumbricales. These are two very small muscles, one of wnich is 

 situated on each side of the tendon of the flexor pedis perforans. 



Origin. From the sides of the perforans tendon. 



Insertion. By a very fine glistening tendon into the fibrous pad behind 

 the fetlock-joint. 



Action. No doubt at one time these muscles played an important part 

 in the function of the foot, but in their present attenuated condition they 

 serve but little or no purpose. 



Extensor Metacarpi Magnus. This is a muscle of considerable 

 size and strength, and gives to the upper part of the arm in front its 

 prominence and width. 



Origin. In common with the extensor pedis from the outer surface 

 of the external condyle, and from the ridge above it. 



Insertion. By a strong tendon which, after passing over a groove on 

 the lower part of the front face of the tibia and the knee-joint, becomes 

 inserted into a bony prominence on the superior and anterior part of the 

 large metacarpal or canon bone. In passing over the knee, the tendon 

 of insertion plays through a synovial sheath, which facilitates its move- 

 ments during flexion and extension of the joint. 



Action. To extend the canon and knee bones on the fore-arm. 



Extensor Metacarpi Obliquus. A small muscle placed on the outer 



side of the lower arm. 



Origin. From the external surface of the radius. 



Insertion. The tendon of this muscle passes obliquely forward and 

 inward over a groove on the radius to reach the inner side of the leg, 

 where it becomes inserted into the head of the inner small metacarpal or 

 splint bone. 



Action. To extend the canon on the fore-arm and rotate it outwards. 



Extensor Pedis. This muscle lies on the outer part of the fore-arm, 

 inclining to the front and immediately behind the extensor metacarpi 



