286 ANATOMY AND PHYSIOLOGY OF THE HORSE^S FOOT. 
appear warrantable; so we will dispense with much of the 
somewhat uninviting details pertaining to a history of their 
origin, insertion, form, and function, and notice at greater 
length more interesting, though not more essential structures. 
It may, therefore, be sufficient to state, with regard to 
these articulations or joints of the foot, that, though main- 
tained in close apposition by ligaments, tendons, and other 
strong fibrous textures of a generally inelastic character, the 
bones we have just described are not allowed to come into 
direct contact with each other save through the medium of a 
variety of cartilage that covers their opposing surfaces, and 
which, by its elasticity, insensitiveness, and very feeble or 
negative vascularity, affords a most efficient means of 
diminishing concussion or jar to the limb, and thus averts 
pain and injury. The composition of this hyaline, true, or 
articular cartilage is well known; it is not covered by a 
synovial membrane, as was at one time imagined, though it 
is stated that it has a lining or surface of pavement epithe- 
lium-cells. Histologically, it is constituted by a homogene- 
ous uniform matrix or fundamental substance, containing a 
more or less abundant proportion of cellular elements ; by 
boiling, this hyaline cartilage yields the substance termed 
chondrine. Its highly polished surface permits extensive 
movement to be easily performed, and while it is completely 
preserved from external disturbance by means of strong 
fibrous capsules or sacs embraced within the ligaments, and 
which hermetically close in the opposing surfaces, the smooth 
aspect of the cartilage is kept constantly lubricated by the 
bland, unctuous, albuminous fluid [synovia) that is continually 
secreted by numerous small tufts hung like fringes around 
the margin of each articulation, and which are dependencies 
of a fine membrane — the synovial — lining the interior of the 
capsule. 
This arrangement is, of course, that common to every 
diathrodial joint, and would not be referred to now but for 
the fact that there is a different arrangement for the move- 
ment of tendons, which has been already casually noticed, 
and which, in a physiological and pathological point of view, 
it is necessary to bear in mind. Before proceeding further to 
a consideration of the tendons, however, there are one or 
two features in the disposition of the ligaments of the foot 
that should be noted, more especially with regard to the 
mode in which these influence its functions. 
It may be said that, in consequence of limiting our ex- 
amination of the limb to the portion commonly designated 
the “foot,” this organ offers only two articulations for study, 
