THE EDINBURGH VETERINARY COLLEGE. 
269 
nest part of the vessel, appeared dilated more than natural, when 
compared with the caliber of the channel above the sinuses and 
below them. In that part of the aorta which contains these si- 
nuses, and which is more especially in connexion with the cavity 
of the pericardium, a rupture of one inch and a quarter was found, 
extending in the same direction as the circular fibres of the middle 
coat. The centre of the rupture internally corresponded with the 
junction of the angles of two semilunar valves. The inner serous 
coat appeared to have given way first, and the fibrous and the 
cellular one afterwards; for between the cellular and fibrous one 
there was a large quantity of extravasated blood. 
It is worthy of remark, that many cases of sudden death among 
horses arise from this cause, the position and form of the rupture 
in such being nearly similar. The rupture appears to be occa- 
sioned by the animal making a sudden or powerful effort, such as 
a spring to gain his feet : perhaps in this case attended with a vi- 
olent struggle, from only having three feet which he could properly 
use, or he might have, from the same cause, slipped in rising. 
Any instantaneous and violent effort may, however, cause the ac- 
cident, and it may also occasionally take place from long continued 
exertion, especially where there has been chronic disease existing. 
On examining the foot in the abovementioned case, a portion of 
cartilage nearly detached was found deeply situated in one of the 
sinuses opening externally. 
Among the cases of sprain, one may be noticed, involving the 
flexor metatarsi and extensor pedis posticus muscles, as being of a 
somewhat rare and interesting nature. A black horse, the pro- 
perty of a carter at Hails Quarry, commenced kicking violently, 
and got his near hind leg over the front of a low stone-cart in 
which he was working. By the violent attempts he had used to 
extricate himself, the leg seemed seriously injured, without shewing 
externally much evidence of such being the case. There was very 
little swelling, no wound or loss of hair, but when made to walk 
the horse was incapable of flexing the hock. The leg, when raised 
from the ground, hung loose and dangling, as if the tibia had been 
fractured. The tendo achilles became quite relaxed, as if it had 
been torn from its superior attachment. An old pupil had been 
called to attend the case, but from the rare occurrence of instances 
of this kind, and its nature being, consequently, rather obscure to 
him, he wished my advice. It was about three miles distant, but, 
being rare, many of the students went and saw it. On examining 
the lame limb, I found there was a slight degree of swelling, with 
pain along the greater part of the flexor metatarsi, which had been 
injured by the strained extension of the limb backwards, while 
fixed over the front of the cart, until it had become powerless, and 
