The rectus muscles are a group of muscles located in the abdomen, primarily responsible for flexing the spine and stabilizing the torso. The most well-known among them is the rectus abdominis, which runs vertically along the front of the abdomen. This muscle is often associated with the "six-pack" appearance in fitness. In addition to the rectus abdominis, there are other rectus muscles, such as the rectus femoris, part of the quadriceps group in the thigh. These muscles play a crucial role in movements like walking, running, and jumping by extending the knee and assisting in hip flexion.