The Rectus Abdominis is contained in the rectus sheath, and the arrangement of the layers has important variations depending upon the location in the body. There are two layers called the Camper’s fascia (anterior part of the Superficial fascia) and Scarpa's fascia ( posterior part of the Superficial fascia) above the rectus sheath.

The aponeurosis is a sheetlike  tendinous expansion, mainly serving to connect a muscle part with the parts it moves. Within the rectus sheath layers will vary. At the lateral margin of the rectus, the aponeurosis of the internal oblique divides into two lamellae (a thin plate, scale, membrane, or layer, as of bone, tissue, or cell walls).

One of which passes in front of the rectus, blending with the aponeurosis of the external oblique. The other, behind it, blending with the aponeurosis of the transversus, and these, joining again at the medial border of the rectus, are inserted into the linea alba.  Since the tendons of the internal obliques and the transversus abdominus only reach as high as the costal margin, it follows that above this level the sheath of the rectus abdominus is deficient behind, the muscle resting directly on the cartilages of the ribs, and being covered only by the tendons of the external obliques.