Answer:
To protect the muscles and vessels.
Step-by-step explanation:
The function of the rectus sheath is to protect the muscles and vessels which it encloses. In addition, keeping the rectus abdominis and pyramidalis muscle together helps in providing maximal compression of and support to abdominal viscera.
The function of the linea alba is to maintain the abdominal muscles at a certain proximity to each other. In the case of long-lasting increased intra-abdominal pressure, the linea alba widens.