Posterior wall of rectus sheath below the level of an anterior superior iliac spine is formed by
The Rectus, where its posterior sheath is deficient (below arcuate line), is separated from the peritoneum only by the transversalis fascia, in contrast to the upper layers, where pa of the internal oblique also runs beneath the rectus. Because of the thinner layers below, this region is more susceptible to herniation.
Internal oblique
Lacunar ligament
Fascia transversalis
Transversus abdominis
Abdomen and pelvis