Which is the longest of the abdominal muscles?

The rectus abdominis is considered the longest of the abdominal muscles because it spans the length of the anterior abdominal wall from the pubic bone to the lower ribs. This muscle is structured in a vertical orientation and extends from the symphysis pubis upwards, making it significant in both its length and functionality. It plays an important role in movements such as flexing the spine and stabilizing the pelvis during activities. This characteristic is what distinguishes the rectus abdominis from the other abdominal muscles, which either run in different orientations or are not as elongated. For instance, the transverse abdominis is more about stabilization and compression of the abdomen but doesn't have the same vertical length. The oblique muscles, both internal and external, are oriented laterally and assist in rotational movements rather than contributing to length in the same way the rectus does.