BACK TENDONS. 37 



the fetlock having lost the support of its powerful brace ; the " bearing " of the 

 foot will not be materially affected. Moller points out that when the perforans 

 tendon has been ruptured, the toe will tend to point upwards if weight be 

 put on the foot ; the cause evidently being that the direction of the weight 

 impressed on the limb falls behind the point of insertion of the perforans 

 tendon on the base of the pedal bone. Hence, it appears that the toe of a 

 sound horse is kept on the ground by the upward pull of the perforans tendon 

 successfully antagonising the downward pressure of the weight borne hy the 

 limb. 



TREATMENT FOR SPRAIN OF THE SUSPENSORY LIGA- 

 MENT. — See page ii et seq. 



Sprain of the Back Tendons and Check Ligament. 



Anatomy of hack tendons and chech ligaments. — There are two back 

 tendons (Figs. 5 and 6) which originate from muscles that help to raise the 



Cannon bone If/ ■I'l 



i'/lk"''l'J I •< Sesamoid bones 



Long pastern bone 



y/ 



Short pastern bone f^^^^D 



/C^L3^ ..' Navicular bone 

 Pedal bone — y^y^:^^"' 



Fig. 9. — Rear view of bones of fetlock and pastern. {After C/iai/veau.) 



foot. From the knee, they run down behind the suspensorj' ligament, one 

 overlying the other. The posterior tendon (the perforatus) forms a sheath 

 for the passage of the other (the perforans) at the back of the fetlock joint, and 

 becomes attached to the short pastern bone (Fig. 6). The perforans tendon 

 is joined halfway down the cannon bone by a powerful ligament which 

 originates at the head of that bone, and at the lower row of the small bones 

 of the knee, having almost the same origin as the suspensory ligament 

 (Fig. 6). This check ligament forms with the lower part of the perforans 

 tendon a strong brace for preventing undue obliquity of the pastern ; its office 

 being very similar to, though less effective than, that of the suspensory liga- 

 ment. The perforans tendon, after affording attachment to the check liga- 

 ment, passes over the sesamoid bones, which act as a pulley for it, then down- 

 the back of the pastern bones, over the third sesamoid or naviculai^ bone (Figs. 

 61 and 70), and is finally inserted on the base of the pedal bone (Fig. 68). 



The parts at which the perforans tendon would be most likely to be 

 sprained, are its attachment to the pedal bone, and the point where it passes 

 over the sesamoid bones. On carefully examining the perforatus — the hind- 

 most one of the two back tendons — we may conclude that it can rarely 

 become injured from excessive tension ; although it is specially liable to suffer 

 from blows inflicted by the hind foot. 



