304 
M. JACOULET, 
internal, formed by the fleshy portion of the small oblique mu 
cle, is very mobile. Easily yielding and spreading, it read! 
permits the dilatation and consequent increase in size of tl 
tract. 
The internal angle or commissure is limited by the prepub 
tendon at its insertion to the pubis. 
The externa] is formed by the insertion of the fleshy fibres ( 
the small oblique upon the crural arch on the external quarter < 
this aponeurosis. 
The inferior opening, which is exposed by the incision of tl 
scrotum and dartos, and by the laceration of the cellular tissi 
beneath, is nothing else than the external inguinal ring. Pierce 
through the aponeurosis of the great oblique, whose fibres se] 
arate in front, to circumscribe its oval shape, this orifice is prii 
cipally well defined on its posterior border or pillar, which 
formed by the crural arch, and at the internal commissure, whic 
is indicated by the prepubic tendon. The other portions of i 
circumference are not well defined on account of the degener: 
tion of the aponeurotic fibres into cellular tissue. It is on th 
account that the entrance to the inguinal tract becomes so ver 
dilatable and so easily susceptible of enlargement. 
The superior orifice, or bottom of the inguinal space, is a kin 
of slit, opening between the superior borders of both walls an 
closed by the peritoneum which rests against its borders. It 
filled with subperitoneal cellular tissue which is continuous wit 
that of the interstice. This slit extends from the insertion of tl 
prepubic tendon to the external quarter of the crural arch, wit 
a length of 15 to 18 centimeters about, and following an obliqv 
direction outward and upward. 
At the internal angle of the interstice, the bottom is sep: 
rated from the entrance or external inguinal ring only by tl 
thickness of the prepubic tendon. But at the external angle th 
distance separating the inferior from the superior opening 
much greater. It appears evident from this that the inguins 
tract increases in depth from its internal to its external angh 
Towards the former, where the inguinal canal is naturally forme 
in the normal, entire horse, as well as in those affected only wit 
