A Spigelian hernia is a variety of an interparietal hernia occurring at the level of the arcuate line.They arise through a defect in the Spigelian fascia, which is the aponeurosis of transversus abdominis. The Spigelian fascia extends between the transversus muscle and the lateral border of the rectus sheath from the costal margin to the groin, where it blends into the conjoint tendon.Often these hernias advance through the internal oblique as well and spread out deep to the external oblique aponeurosis. Most Spigelian hernias appear below the level of the umbilicus near the edge of the rectus sheath, but they can be found anywhere along the Spigelian lineBailey and Love27e pg: 1041