AN ESSAY ON CHRONIC PODOTROCHOLITIS. 
409 
pearance of having been submitted to lateral compression ; exa- 
mined on its anterior surface, it looked as if wrinkled. I attribute 
this alteration to a degree of compression exercised by the heels of 
the coffin bone, the result of their near approach to each other in 
hoof-bound feet. When the navicular bone is inflamed, it is red 
and strongly injected ; the vessels which traverse it, and the cells 
and canals with which it is perforated, are dilated. When mace- 
rated, it is found to have decreased in weight, its texture to have 
become more porous, and sometimes it appears a little puffed up, 
( osteoporose .) 
If the disease has made some progress on that side of the bursal 
mucous membrane next to the tendon, or that which faces the 
navicular bone, or both, have undergone partial destruction, and 
the tendinous fibres are denuded, a reabsorption of a portion of the 
trochlean cartilage is also not unfrequently met with, particularly 
near the crest of the navicular ; again, the posterior surface of this 
bone has often become partially absorbed on the two sides border- 
ing on the crest. Its projection, becoming enlarged, imprints a 
longitudinal groove of greater or less depth in the flexor tendon, on 
which it rests. This process of destruction of the trochlean carti- 
lage is caused, according to Herbert Mayo*, by the absorbing 
action of the cartilage itself ; but this pathological phenomena, as 
well as that which takes place on the surface of the navicular, seems 
to admit of being classed under that species of absorption called 
by Thomson progressive , and having for its cause a purely me- 
chanical action. The diminution of the frontal bone, the result of 
compression of cerebral tumour, and the depression upon the nose 
by the nose band, present us with analogous examples of bony 
reabsorptions. If the comparison is not exact, at least there is no 
striking difference ; and what speaks strongly in its favour is, that 
the disappearance of the bony matter corresponds exactly to the 
parts where the navicular is compressed by the branches of the 
frog. 
Round about the groove formed in the flexor tendon the super- 
ficial fibres of this latter separate themselves from those immedi- 
ately beneath, sometimes only on one, at others on both sides. At 
first they commence by merely disuniting among themselves ; after- 
wards they break at one extremity or the other, roll up on them- 
selves, and form little elevations on the level of the tendon. The 
loss of substance which thus results confounding itself with the 
longitudinal groove already formed, still further increases its size. 
At this period of chronic podotrocholitis the flexor tendon fre- 
* Gundniss der speciellen Pathologie, mit besonderer Rucksicht auf die 
pathologische anatomie. Translated from the English, 1838. 
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