It’s the thickened inferior margin of the fascia transversalis which appears as a fibrous band running parallel and posterior to the inguinal ligament. When the inguinal region is viewed from its posterior aspect, the iliopubic tract is observed in place of the inguinal ligament.

According to Fruchaud, the inguinal ligament and iliopubic tract span a congenital area of weakness in the inguinal region.