r will the
hernia force a way at a point external to the femoral vessels in
preference to that of the crural canal, which is already prepared to
admit it. [Footnote] The bowel, therefore, enters the femoral canal, 9,
and herein it lies covered by its peritonaeal sac, derived from that
part of the membrane which once masked the crural ring. The septum
crurale itself, having been dilated before the sac, of course invests it
also. The femoral canal forms now the third covering of the bowel. If in
this stage of the hernia it should suffer constriction, Gimbernat's
ligament, 8, is the cause of it. An incipient femoral hernia of the size
of 2, 12, cannot, in the undissected state of the parts, be detected by
manual operation; for, being bound down by the dense fibrous structures
which gird the canal, it forms no apparent tumour in the groin.

[Footnote: The mode in which the femoral sheath, continued from the
abdominal membrane, becomes simply applied to the sides of the vessels,
renders it of course not impossible for a hernia to protrude into the
sheath at any point of its abdominal entrance. Mr. Stanley and M.
Cloquet have observed a femoral hernia external to the vessels.
Hesselbach has also met with this variety. A hernia of this nature has
come under my own observation. Cloquet has seen the hernia descend the
sheath once in front of the vessels, and once behind them. These
varieties, however, must be very rare. The external form has never been
met with by Hey, Cooper, or Scarpa; whilst no less than six instances of
it have come under the notice of Mr. Macilwain, (on Hernia, p. 293.)]

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
PLATE 45.--FIGURE 5

PLATE 45, Fig. 6.--The hernia, 2, 12, increasing gradually in size,
becomes tightly impacted in the crural canal, and being unable to dilate
this tube uniformly to a size corresponding with its own volume, it at
length bends towards the saphenous opening, 6, 7, this being the more
easy point of egress. Still, the neck of the sac, 2, remains constricted
at the ring, whilst the part which occupies the canal is also very much
narrowed. The fundus of the sac, 9*, 12, alone expands, as being free of
the canal; and covering this part of the hernia may be seen the fascia
propria, 9*. This fascia is a production of the inner wall of the canal;
and if we trace its sides, we shall find its lower part to be continuous
with the femoral sheath, w