Final answer:
The linea alba separates the left and right portions of the rectus abdominis muscles, which contribute to the 'six-pack abs' look.
Step-by-step explanation:
The linea alba separates the left and right portions of the rectus abdominis muscles, which are often referred to as the "sit-up" muscles. These muscles are responsible for the appearance of "six-pack abs" and extend along the body's trunk from the pubic crest and symphysis. The linea alba itself is a white, fibrous band composed of the joined bilateral rectus sheaths at the body's anterior midline, encasing the rectus abdominis muscles. The muscles are segmented by tendinous intersections, contributing to their segmented appearance.