ous
membrane of the abdomen. They originate from nearly the same locality.
The ring of the femoral canal, 12, is situated immediately below, but to
the inner side of the internal inguinal ring, 3. The epigastric artery,
1, marks the width of the interval which separates the two rings.
Poupart's ligament, 5, being the line of union between the oblique
aponeurosis of the abdominal muscle and the fascia lata, merely
overarches the femoral sheath, and does not separate it absolutely from
the spermatic sheath.

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
PLATE 45.--FIGURE 2

PLATE 45, Fig. 3.--The peritonaeum, 2, 3, closes the femoral canal, 12,
at the femoral ring, in the same way as this membrane closes the
inguinal canal at the internal inguinal ring, 3, Fig. 2, Plate 45. The
epigastric artery always holds an intermediate position between both
rings. The spermatic vessels in the inguinal tube, 3, 3, Fig. 2, Plate
45, are represented by the round ligament in the female inguinal canal,
Fig. 3, Plate 45. When the bowel is about to protrude at either of the
rings, it first dilates the peritonaeum, which covers these openings.

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
PLATE 45.--FIGURE 3

PLATE 45, Fig. 4.--The place of election for the formation of any hernia
is that which is structurally the weakest. As the space which the
femoral arch spans external to the vessels is fully occupied by the
psoas and iliacus muscles, and, moreover, as the abdominal fibrous
membrane and its prolongation, the femoral sheath, closely embrace the
vessels on their outer anterior and posterior sides, whilst on their
inner side the membrane and sheath are removed at a considerable
interval from the vessels, it is through this interval (the canal) that
the hernia may more readily pass. The peritonaeum, 2, and crural septum,
13, form at this place the only barrier against the protrusion of the
bowel into the canal.

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
PLATE 45.--FIGURE 4

PLATE 45, Fig. 5.--The hernia cannot freely enter the compartment, 10,
occupied by the artery, neither can it enter the place 11, occupied as
it is by the vein. It cannot readily pass through the inguinal wall at a
point internal to, 9, the crural sheath, for here it is opposed by, 4,
the conjoined tendon, and by, 8, Gimbernat's ligament. Neithe