The rectus abdominis muscle is a long, thin muscle located in the anterior region of the abdomen. It originates at the pubic symphysis and pubic crest of the pelvis, and inserts into the xiphoid process and costal cartilages of the fifth to seventh ribs. The rectus abdominis muscle is one of several muscles that make up the anterior abdominal wall, and is commonly known as the "abs".

The main function of the rectus abdominis muscle is to flex the spine, bringing the chest towards the pelvis. This movement is essential for activities such as sit-ups and crunches, and helps to provide stability and support for the trunk. The rectus abdominis muscle also helps to laterally flex (bend to the side) the spine and rotate the trunk.

In everyday life, the rectus abdominis muscle is used in many activities that involve flexion of the spine, such as sit-ups and crunches. It is also used in activities that require stability and support for the trunk, such as lifting a heavy object or bending over to pick something up.