ON PORSO-LUMBAR SPRAIN IN THE HORSE. 43 
which is situated precisely in the middle of the dorso-lumbar 
spine, and, consequently upon it, it is that all effort of any kind 
becomes concentrated, let it come in what direction it may, 
from below upward or from above downward. In other and 
rarer cases, it happens quite in the anterior part of the dorsal 
spine, in the articulation between the second and third dorsal 
vertebrae, or in that between the third and fourth; or, else, in 
that between the seventeenth and eighteenth vertebrae. 
The greater frequency of the accident in the lumbar vertebrae 
than elsewhere becomes satisfactorily explained on the score 
of the lumbar being in every way the most moveable portion of 
the spine. 
As to the dislocation of the lumbo-sacral vertebrae, of which 
Garsault has spoken, I believe it possible in the ox, on account 
of the anatomical construction of his spine, and most rare, if 
indeed possible, in horses, for the same reason. 
Let us now consider the spinal lesions; which are, Istly, 
on the vertebrae themselves (lesions of the bones); 2dly, on 
the articulations (lesions of the articulatory surfaces and their 
means of repair). 
The Lesions of the Bones which one remarks around 
the vertebrae, as consequences of the causes but now detailed, 
may be with reason regarded as means employed by nature to 
give greater resistance to the spinal column, as a sort of re¬ 
paration of the damages it has sustained in the dorso-lumbar 
region. In fact, these are veritable ossific vegetations, veritable 
buttresses, variable in their spread, running from one vertebra 
to another. 
These osseous vegetations, which some authors have named 
osteophytes , most commonly make their appearance first along 
the inferior surface in the dorsal region, reaching the sides 
of the bodies of the vertebrae but by degrees, or, else, they 
surround all at once the vertebral amphiarthrosis. In the 
lumbar vertebrae, as I have formerly endeavoured to account 
for by their greater mobility, it is most commonly found upon 
the lateral parts, either on one or both sides of them at once. 
These ossifications at times assume a knotty aspect upon the 
bodies of the vertebrae, pushing the posterior aorta more or less 
out of its place, and sometimes surrounding it in such manner 
that the vessel has to run through a bony canal. In the 
lumbar region, the less psoas muscle sometimes experiences a 
deviation of its fibres, with more or less discolouration of them. 
At the anterior part of the dorsal region the thoracic portion of 
the levator humeri becomes more or less altered. 
When osseous tumours are recent, there appears a very re¬ 
markable sanguineous vascular development upon their surface, 
and sometimes even upon the neighbouring organs (aorta and 
grand sympathetic nerve, &c.); whereas, on the contrary, when 
they are old, they have the ordinary taint of osseous tissue. 
