Final answer:
The anterior layer of the rectus sheath below the arcuate line consists of the external oblique, internal oblique, and transversus abdominis aponeuroses.
Step-by-step explanation:
The composition of the anterior layer of the rectus sheath below the arcuate line consists of the external oblique, internal oblique, and transversus abdominis aponeuroses. The external oblique muscles form the outermost layer, followed by the internal oblique muscles in the middle layer, and finally the transversus abdominis muscle as the deepest layer.