ON LAMENESS FROM STRAINS. 271 



These, then, are the tv/o tendons, which, taken together, form 

 the back sinews. Between these two tendons there are, in two 

 parts, thin membranes, by which they are joined together ; these 

 membranes appear to serve as bridles, allowing the perforans ten- 

 don to move a little way within the perforatus, and then pi-event- 

 ing any further motion. The situation of those membranes is 

 about midway in the leg, and midway in the pastern. If the 

 coffin joint happen to be extended in a way the animal was not 

 prepared for, both these membranes are ruptured. The conse- 

 quence is, an effusion of blood between the two tendons. 



It will be seen from the Plate that there is a strong ligament, 

 but in appearance like a tendon, coming from the back part of the 

 knee, passing down about four or five inches, and then incor- 

 porating with the perforans tendon. This I have named the 

 great ligament of the back sinew, and its office is of a very im- 

 portant nature, being no less than that of supporting the whole 

 body ; that is, supposing the flexor muscles to be fatigued, and 

 incapable of doing it, and in consequence giving way ; for in 

 that case this great ligament forming one rope with the great 

 back sinew, and this sinew being firmly inserted into the bottom 

 of the coffin bone, it must of necessity be the sole support of the 

 whole w^eight. This ligament may also be ruptured in strains. 

 I have seen a case of this kind, and such must have been the 

 cases that have been described as a rupture of the back sinew, 

 an accident, as must be obvious from the plate*, that cannot 

 happen. 



One part only remains to be described, and that is the 

 suspensory ligament. This ligament passes down from behind 

 the knee close to the shank bone, until it arrives to within 

 three inches and a half of the superior and posterior part of the 

 sesamoid bones : at this part it divides into two branches, which 

 diverge from each other, and embrace the sesamoid bones 

 laterally, so as to keep them firmly in their situations ; it then 

 passes downward, ancl obliquely forward, and gains the extensor 

 tendon about midway, in front of the pastern. This ligament is 

 the chief support of the fetlock joint, and is sometimes ruptured 

 in one of its branches : this, however, is rarely the case ; but it 

 is much more frequently strained and enlarged. 



The fetlock joints are of great importance to the horse: they 

 receive, from their oblique position with respect to the legs, the 

 Aveight of the whole body, and form that important spring which 

 enables him to perform his wonderful exertions with ease to 

 himself and pleasure to his rider. From this circumstance, they 



* A. The outside nerve, or that part of it where the branch II communi- 

 cates. B. The suspensory ligament. C. The great ligament of the back 

 sinew, D. The two back sineVs, or flexor tendons. EE. The extensor ten- 



