246 THE EXTERIOR OF THE HORSE. 



The latter opinion is nowadays most generally accepted. Be this as it may, the 

 accident occurs but once, or again its reproduction may be intermittent and 

 frequent, the bone becoming alternately dislocated and reduced spontaneously at 

 the end of a variable period. In either case a very intense lameness supervenes, 

 the chief diagnostic character of which consists in the attitude of the member, 

 which remains in a state of forced extension, and can only be carried forward by 

 a very marked abductive movement. A horse in such a state is, of course, not in 

 a condition to be sold, unless, however, the sale should be made during the 

 interval of two displacements of the patella, as we have had occasion to observe 

 several times. 



5th. Traces of blisters and cauterization denote that the region has 

 been treated for one of the diseases of which we have just spoken, principally 

 synovial dilatations. 



C. The Leg. 



Situation; Limits; Anatomical Base. The leg is the in- 

 termediate region between the thigh and the hock ; the stifle and the 

 buttock are also its upper boundaries. 



Two bones form its resisting, osseous base : the tibia and the peroneus. The 

 latter is so rudimentary in the horse that it is hardly of any account so far aa 

 animal mechanics are concerned. The tibia, on the contrary, strong and pris- 

 matic, is situated obliquely from above downward and from before backward 

 under the femur, to which it is joined by a very movable articulation. 



Two groups of powerful muscles cover it in front, on the back, and on the 

 outside. Its internal face alone is subcutaneous, and therefore more exposed to- 

 traumatisms. The function of the anterior tibial muscles is the flexion of the 

 canon and the extension of the phalanges upon each other and upon the meta- 

 carpus. The role of the posterior tibial muscles is precisely the reverse : with the 

 exception of one, the popliteus, they are all extensors of the metacarpus or 

 flexors of the digital region. They are, in a great measure, concealed externally 

 by the inferior extremity of the ischio-tibial muscles which cover them. Lastly, 

 most of them become inflected over the back part of the hock, that is to say, 

 the summit of the tibio-tarsal angle, and by this very fact help to prevent the 

 closing of this angle when the member is standing still. 



External Form. The tibial muscles, like those of the antibrachial region, 

 have this peculiarity, that above they are constituted by a fleshy body, and below 

 they are continued by a shorter or a longer tendon, destined to transmit their action 

 to the canon or to the phalanges. The result of this is that the region, considered 

 as a whole, presents a somewhat pyramidal or conical form, wider above than 

 below, and compressed from one side to the other. Four faces may be recognized 

 on this region, two of which, the external and the internal, especially merit our 

 attention. 



The external face, almost plane superiorly, and confounded with the 

 most declivitous part of the thigh and the buttock, shows quite distinctly the 

 outlines of the muscles that we have mentioned above. Inferiorly, there is a 

 change in its appearance near the hock : the external tuberosity of the tibia may 

 be discerned in front, the anterior border of the calcanetis behind, and between 

 these two eminences a depression which is called the hollow of (he hock. It is 



