Page 80 - Clinical Anatomy

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Peritoneal cavity 65

•◊◊three other structures—the vas deferens, lymphatics of the testis, which
pass to the para-aortic lymph nodes and, pathologically present as the third
structure, a patent processus vaginalis in patients with an indirect inguinal
hernia!

Clinical features

An indirect inguinal hernia passes through the internal ring, along the canal
and then, if large enough, emerges through the external ring and descends
into the scrotum. If reducible, such a hernia can be completely controlled by
pressure with the fingertip over the internal ring, which lies 0.5in (12mm)
above the point where the femoral artery passes under the inguinal liga-
ment, i.e. 0.5in (12mm) above the femoral pulse. This pulse can be felt at the
mid-inguinal point, half-way between the anterior superior iliac spine and
the symphysis pubis (see Fig. 153).
If the hernia protrudes through the external ring, it can be felt to lie
above and medial to the pubic tubercle, and is thus differentiated from a
femoral hernia emerging from the femoral canal, which lies below and
lateral to this landmark (see Fig. 176).
A direct inguinal hernia pushes its way directly forwards through the
posterior wall of the inguinal canal. Since it lies medial to the internal ring, it is
not controlled by digital pressure applied immediately above the femoral
pulse. Occasionally, a direct hernia becomes large enough to push its way
through the external ring and then into the neck of the scrotum. This is so
unusual that one can usually assume that a scrotal hernia is an indirect hernia.
The only certain way of determining the issue is at operation; the infe-
rior epigastric vessels demarcate the medial edge of the internal ring, there-
fore an indirect hernia sac will pass lateral and a direct hernia medial to
these vessels. Quite often both a direct and an indirect hernia coexist; they
bulge through on each side of the inferior epigastric vessels like the legs
of a pair of pantaloons.

Peritoneal cavity

The endothelial lining of the primitive coelomic cavity of the embryo
becomes the thoracic pleura and the abdominal peritoneum. Each is invagi-
nated by ingrowing viscera which thus come to be covered by a serous
membrane and to be packed snugly into a serous-lined cavity, the visceral
and parietal layer respectively.
In the male, the peritoneal cavity is completely closed, but in the female
it is perforated by the openings of the uterine tubes which constitute a pos-
sible pathway of infection from the exterior.
To revise the complicated attachments of the peritoneum, it is best to
start at one point and trace this membrane in an imaginary round-trip of
the abdominal cavity, aided by Figs 47 and 48. A convenient point of