Urogenital disorders

III./1.6.: The inguinal canal

III./1.6.1.: The inguinal canal and the abdominal hernias

The weak areas of the abdominal wall are potential sites of hernias. In case of increased intraabdominal pressure (e.g. coughing, lifting, or when babies cry) the contents of the abdominal cavity (e.g. omentum, intestines) are moving into the direction of the least resistance and can develop hernia there. There is a life-threatening condition when herniated tissue is trapped in the hernial sac (can not be pushed back, incarceration of hernia), can cause death of the patient therefore makes an absolute indication for surgery.

There are two weak regions of the abdominal wall at the region of the inguinal canal: the lateral inguinal fossa (= deep inguinal ring) and the medial inguinal fossa (= superficial inguinal ring). When an abdominal hernia develops through one of these areas it is called inguinal hernia. If the inguinal hernia is made via the lateral inguinal fossa (deep inguinal ring), the contents of the hernia join to the structures which normally pass through there, in this case the hernia contents also pass through the inguinal canal; this is called lateral inguinal hernia (indirect hernia).

If the weaker area of the medial inguinal fossa (superficial inguinal ring), is protruded, medial inguinal hernia (direct hernia) is created. Here the aponeurosis of the external abdominal oblique muscle is missing from the layers of the abdominal wall) and the fused aponeuroses of the internal abdominal oblique and transversus abdominis muscles form the inguinal falx aponeurotica (conjoint tendon) which gives the posterior wall of the inguinal canal close to the superficial inguinal ring; this is an area of weakness in the abdominal wall in case of direct hernia. In this case the inguinal canal contains no herniated structures. The inguinal hernia can be connatal (wrong name: congenital) when the baby is born with it due to the patent processus vaginalis peritonei, causing indirect hernia – the other inguinal hernias can be acquired. The latter ones can be both direct and indirect hernias.

III./1.6.2.: The anatomy of the inguinal canal

The inguinal canal is found on the anterior abdominal wall; it is an obliquely running, approx. 4-5 cm long channel, running above and located parallel with the inguinal ligament. Its openings: the deep (internal) inguinal ring (anulus inguinalis profundus) is located at the inner aspect of the abdominal wall in the lateral inguinal fossa. This is a depression on the lateral side of the lateral umbilical fold (the peritoneal fold formed by the inferior epigastric artery and veins). The parietal peritoneum closes it toward the abdomen, but the transversal fascia has its funnel-like extension surrounding the structures passing here between the layers of the abdominal wall.

The superficial (external) inguinal ring (anulus inguinalis superficialis) is discernible on the outer side of the abdominal wall, at the level of the medial inguinal fossa. The superficial inguinal ring is found medially and inferiorly from the deep inguinal ring. The ring is created by the diverging fibers of the aponeurosis of the external abdominal oblique muscle. This opening is located above the inguinal ligament (of Poupart); the other borders are the medial and lateral crura of the aponeurosis of the external abdominal oblique muscle and the intercrural fibers (from above). The inguinal canal is a real passage where structures normally go through (unlike e.g. the femoral canal, which is only a virtual, preformed space, having contents just in case of hernia).

III./1.6.3.: The walls of the inguinal canal

• -Anterior: aponeurosis of the external abdominal oblique muscle,

• -posterior: the transversal fascia and the lower edge of transversus abdominis muscle,

• -superior: internal abdominal oblique muscle and partly the transversus abdominis muscle (their lower margins),

• -inferior: inguinal ligament (of Poupart).

III./1.6.4.: The contents of the inguinal canal

In males the spermatic cord; in females the round ligament of the uterus; in both sexes the ilioinguinal nerve also.