A tube made of the transversalis fascia and the aponeuroses of the abdominal wall muscles just above the inguinal ligament. The inguinal canal is a cylindrical passageway 4 cm long from the retroperitoneal space to the skin. It begins at the deep (internal) inguinal ring inside the abdominal wall, approx, halfway between the anterior superior spine of the iliac bone and the pubic symphysis, 1.25 cm above the inguinal ligament. It continues down and toward the midline, and it ends at the superficial (external) inguinal ring under the skin at the pubic crest. The inguinal canal contains an outpouching of the peritoneum, blood and lymph vessels, and the ilioinguinal nerve. In males, it also contains the spermatic cord; in females, it also contains the round ligament of the uterus.