Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The rectus abdominis muscle, also known as the "6-pack," is a paired muscle running vertically on each side of the anterior wall of the human abdomen (and in some other animals). There are two parallel muscles, separated by a midline band of connective tissue called the linea alba (white line). It extends from the pubic symphysis/pubic crest inferiorly to the xiphisternum/xiphoid process and lower costal cartilages (5 7) superiorly. It is contained in the rectus sheath. The rectus is usually crossed by three fibrous bands linked by the tendinous intersections.