integuments, adipous membrane, and superficial fascia, of a length and
depth sufficient to expose the tendon of the external oblique muscle for
an inch or so above the external ring; and the hernia for the same
extent below the ring. The length of the incision will require to be
varied according to circumstances, but its direction should be oblique
with that of the hernia itself, and also over the centre of its
longitudinal axis, so as to avoid injuring the spermatic vessels. If the
constriction of the hernia be caused by the external ring, a director is
to be inserted beneath this part, and a few of its fibres divided. But
when the stricture is produced by either of the muscles which lie
beneath the aponeurosis of the external oblique, it will be necessary to
divide this part in order to expose and incise them.

When the thickened and indurated neck of the sac is felt to be the cause
of the strangulation, or when the bowel cannot be replaced, in
consequence of adhesions which it may have contracted with some part of
the sac, it then becomes necessary to open this envelope. And now the
position of the epigastric artery is to be remembered, so as to avoid
wounding it in the incision about to be made through the constricted
neck of the sac. The artery being situated on the inner side of the neck
of the sac of an oblique hernia, requires the incision to be made
outwards from the external side of the neck; whereas in the direct
hernia, the artery being on its outer side, the incision should be
conducted inwards from the inner side of the neck. But as the external
or oblique hernia may by its weight, in process of time, gravitate so
far inwards as to assume the position and appearance of a hernia
originally direct and internal, and as by this change of place the
oblique hernia, becoming direct as to position, does not at the same
time become internal in respect to the epigastric artery,--for this
vessel, F, Plate 35, has been borne inwards to the place, G, where it
still lies, internal to the neck of the sac, and since, moreover, it is
very difficult to diagnose a case of this kind with positive certainty,
it is therefore recommended to incise the stricture at the neck of the
sac in a line carried directly upwards. (Sir Astley Cooper.) It will be
seen, however, on referring to Plates 32, 33, 34, 35, 36, 37, & 38, that
an incision carried obliquely upwards towards the umbilicus would be
much more likely to avoid the epigastr